1. Symptoms and evidence
- Water leaking from waste/overflow area.
- Floor became wet near machine.
- Main cooler section reported as overheating.
- Engineer fitted overflow tube to catch container.
Search this equipment page
Find overflow, fan noise, water bath, pump, condenser, or handover notes
Streamlined issue briefs
Postmix issue branches · same Manchester asset
Each branch follows the same four-part template so repeat postmix faults stay separated.
Open / monitoringWaste overflow leak and overheating concern
2. Suspects
- Overflow not routed to drain.
- Water bath overfilled.
- Blocked/kinked overflow tube.
- Ice-bank/water-bath control issue.
- Condenser airflow/overheating or separate push-fit leak.
3. Expand resources
Manual / how-to / error reference
Optima 7 spec sheet and Multiplex parts catalogue are saved below.
Troubleshooting tests
Monitor catch-container fill rate, check tube slope/kinks, inspect push-fit leaks, clean external condenser grille, and keep ventilation clear.
Diagram / parts / sources
Reference parts include BA45137 water bath and SA48973 soda pump assembly. Do not order until engineer confirms.
4. Updated solution/status
Monitoring: tube-to-container is a workaround, not confirmed root-cause repair.
ResolvedLoud knocking/rattling from loose condenser fan
1. Symptoms and evidence
- Loud mechanical knocking as if something hit inside.
- Engineer inspected condenser area.
- Fan was loose and hitting casing/side.
2. Suspects
- Loose fan mounting screws/bracket.
- Fan blade/guard/casing contact.
- Worn fan motor bearing or debris.
- External stock pressing panel/grille inward.
3. Expand resources
Manual / how-to / error reference
Use Optima 7 parts/spec references and condenser airflow notes.
Troubleshooting tests
Record sound, power off before close inspection, clear external obstructions, ask engineer to check fan clearance, bracket, guard, blade and bearing.
Diagram / parts / sources
Fan/condenser parts should be confirmed by Abevco/Multiplex engineer before ordering.
4. Updated solution/status
Resolved: engineer found loose condenser fan and corrected/repaired it.
ResolvedSticky Wunder-Bar M4 postmix gun buttons
1. Symptoms and evidence
- Large Coke/soda pours kept running because buttons stuck down.
- Had to press buttons several times to stop flow.
- Video evidence saved, compressed silent because visual is enough.
2. Suspects
- Syrup/sugar residue under buttons/nozzle.
- Binding button/butterfly plate or overtightened screws.
- Worn/swollen O-rings, valve plungers or springs.
3. Expand resources
Manual / how-to / error reference
Wunder-Bar M4 manual and CokeSolutions cleaning guide are saved below.
Troubleshooting tests
Warm soapy/sanitising soak, toothbrush/nozzle brush clean, soda-water flush, identify affected button, then call engineer if still sticking.
Diagram / parts / sources
M4 manual references buttons/plate, butterfly plates, stem O-rings and valve plunger assembly. Engineer ultimately replaced/repaired gun/head.
4. Updated solution/status
Resolved: cleaning did not fully solve; engineer repaired/replaced gun/head.
Issue history for this postmix cooler
Choose the problem type
This physical postmix cooler now has its own equipment page for the Manchester site. Because similar Abevco/Optima-style postmix systems exist across the sites, this page can also be used as the reference template for the same issue elsewhere.
Open / monitoring · 2026-05-23
Waste overflow leak and overheating concern
Water was seen spilling near the Optima 7 waste/overflow area. Engineer fitted a tube from the overflow/waste outlet into a container as a catchment workaround.
Open troubleshooting logResolved · 2026-05-09
Loud knocking / rattling — loose condenser fan
Machine made loud internal knocking noises as if something was hitting inside. Engineer found the condenser fan loose and striking the side/casing.
Open fan-noise branchResolved · 2026-05-12
Sticky postmix gun buttons
Large drinks such as Coke and soda continued pouring because buttons stuck down. Cleaning/soaking was tried; engineer ultimately replaced the gun/head.
Open sticky-gun branchPoor carbonation / flat drinks
No issue logged yet.
Soda pump / recirculation fault
No issue logged yet.
No cooling / warm drinks
No issue logged yet.
Evidence photos
Before leak evidence and after engineer workaround
The first photos show leakage around the waste/overflow area and floor. The final photo shows the tube fitted to divert water into a catch container.
Diagnosis
Most likely reasons for overflow leaking
Fact-check: an Optima 7 is a water-bath / ice-bank postmix shelf cooler. A water-bath overflow outlet is normal, but water should be safely routed to drain or a suitable container. If it is repeatedly discharging, investigate why the bath is gaining too much water or why it is not draining properly.
- Overflow not routed to a drain: the simplest cause is that the overflow is doing its job, but emptying onto the machine/floor because no drain line or container was fitted.
- Water bath overfilled: the Optima 7 spec sheet lists a 10 litre water bath capacity. Overfilling can cause overflow, especially once the ice bank forms/displaces water.
- Blocked, kinked, or misrouted overflow tube: if the overflow/waste tube is obstructed, water can back up and spill from the wrong point.
- Ice-bank / cooling control issue: poor ice-bank control or thawing/refreezing can change water level and cause excess overflow. Parts reference identifies the ice bank control as a Ranco mechanical stat.
- Condensation from poor airflow / overheating: a dirty condenser, failed condenser fan, blocked grille, or high ambient temperature can make the unit run hot and create extra condensation/water around the unit.
- Loose John Guest / push-fit fitting or split tube: leaks around syrup/water/soda lines can be mistaken for overflow. Check each fitting while the unit is running.
- Soda recirculation/carbonator leak: the Optima 7 includes a soda recirculation pump and carbonator supply; leaks from those circuits should be investigated separately from the water-bath overflow.
Fact check of engineer workaround
Tube to catch container: acceptable temporary control, not root-cause fix
Fitting a tube to lead overflow water into a container is plausible and sensible as a temporary safety/workaround measure because it stops water spilling over the floor and near electrics. However, it does not prove the machine is healthy. If the container fills frequently, the underlying cause still needs diagnosing: overfilled bath, blocked drain/overflow, overheating/condenser issue, water-bath/ice-bank control issue, or a separate line leak.
Current next action: monitor how quickly the container fills, keep it emptied, check for heat/airflow issues, and ask Abevco/Multiplex engineer to confirm whether overflow discharge rate is normal for this Optima 7 or whether the water bath / ice bank / drain route needs service.
Issue branch · Resolved 2026-05-09
Loud knocking / rattling from inside machine
Confirmed engineer diagnosis: the condenser fan inside the machine was loose and was hitting the side/casing. This fits the symptom very strongly because the noise was loud, mechanical, and sounded like something repeatedly striking inside the unit.
- Why this was likely definite: the engineer physically inspected the condenser area and found the fan loose and making contact. A rotating fan blade or fan guard contact will create a repeated knocking, ticking, scraping, or rattling noise that changes when the fan starts/stops.
- Common causes: loose fan mounting screws/bracket, bent fan guard, fan blade shifted on shaft, vibration from compressor/cabinet, debris caught near fan, worn fan motor bearing, or casing/panel pushed close to the fan.
- Why it matters: if the condenser fan cannot spin freely, the condenser cannot reject heat properly. That can make the cooler run hot, reduce cooling performance, increase compressor strain, and potentially contribute to overheating faults.
- Do not ignore: continued fan contact can damage the blade, motor, wiring, condenser coil, or casing.
Issue branch · Resolved 2026-05-12
Sticky postmix gun buttons
Symptom: when pouring larger drinks such as Coke or soda, one or more buttons on the postmix gun stuck down and the drink would not shut off until the button was pressed again several times. Cleaning was attempted, but the gun was ultimately repaired/replaced by an engineer and is working now.
- Likely gun type: the video frame shows an M4 marking, which matches a Wunder-Bar Mark 4 / M4 mechanical postmix gun. Confirm from any label/engineer paperwork if available.
- Most likely causes: sticky syrup/sugar residue under buttons or around the nozzle, dried Coke/syrup deposits inside the button plate, worn or swollen O-rings, sticky valve plunger, over-tightened button/butterfly plate screws causing binding, weak spring return, or damaged button/plate parts.
- Why cleaning was the right first step: soda guns are exposed to sugar syrup and splashback, so sticky buttons are commonly caused by residue. Warm cleaning solution, soaking, flushing, and brushing are standard first-line fixes.
- Why replacement was reasonable: if buttons still stick after thorough cleaning and flushing, the fault is more likely internal wear/binding — valve plunger, spring, stem O-ring, button plate, or gun body — so engineer replacement of the gun/head is a sensible final fix.
What can be dismantled / investigated
Manual-backed checks for the M4 gun
The Wunder-Bar M4 manual says the button plate and buttons can be removed, and that the dispenser is a non-electric mechanical valve gun. It also warns not to overtighten retainer or button-plate screws because this can cause binding. Internal valve/O-ring/plunger work should be done by a competent drinks-dispense engineer unless staff are specifically trained.
Check for binding
The M4 manual describes removable buttons, button plate, and butterfly plates. If screws are over-tightened or residue builds under the plate, buttons can bind/stick.
Staff: clean externally. Engineer/trained staff: remove plate and inspect.Valve plunger assembly
The manual references valve plunger replacement when product leaks through the nozzle. Sticky or worn plunger/spring action could also explain a button that does not return/shut off cleanly.
Engineer repair item — do not order until confirmed.O-ring / seal condition
The manual describes stem O-ring replacement where syrup/soda/water leaks under the button plate. Damaged or swollen seals can create drag or leaks.
Engineer repair item — requires correct tool/procedure.Video evidence
Click-to-play fault examples
Videos should be stored on the equipment page with normal browser controls and no autoplay. For visual-only faults like sticky buttons, the clip is compressed without audio so it loads faster on phones.
Fan-noise video pendingSend or upload the original MP4 for VID_20260509_203134.mp4 and I’ll add it here with audio controls.
Manual / parts references
What I found publicly
I found the official Multiplex Optima 7 spec sheet and the Welbilt Halesowen Multiplex spare parts catalogue. I have not yet found a full public Optima 7 service manual with exploded diagrams specific to this machine.
Official spec sheet
Confirms the unit type, water bath capacity, compressor, refrigerant, condenser fan, ice bank control, soda recirculation pump, and coil layout.
Open downloaded PDF Source: Multiplex Beverage Key: 10L water bath · 862.5W · R134a · 16W condenser fan — relevant to fan-noise issueWater bath — Optima 7
Parts catalogue page lists BA45137 as the Optima 7 water bath under “Baths, drains & overflows”.
View parts page image Open parts catalogue PDF Useful for engineer discussion, not a confirmed required replacement.Soda pump assembly — Optima 7
Parts catalogue lists SA48973 as “Soda pump assembly (Optima 7)”. Relevant if soda recirculation/carbonation side is leaking or overheating.
View parts page image Only replace after engineer confirms pump/circuit fault.
Postmix gun manual
Manual for 1–14 button postmix and juice dispensers. Includes button/butterfly plate notes, repair sections, cleaning/sanitising, and troubleshooting.
Open downloaded PDF Source: Wunder-Bar Relevant to sticky buttons, binding plates, O-rings, and valve plungers.Bar gun cleaning / sanitising
Coca-Cola bar gun cleaning guide confirms daily cleaning ideas such as sanitiser solution, nozzle brush, soaking difficult nozzles, and flushing buttons.
Open downloaded PDF Source: CokeSolutions Useful cleaning reference; follow chemical dilution/safety instructions.Reference images
Spec sheet and parts catalogue extracts
Engineer handover
Copy / paste message
Postmix machine issue at Bunk Manchester, 48 Portland Street, Manchester M1 4QU: Abevco-supplied Multiplex Optima 7 shelf cooler, serial seen 20170920G014, located around the postmix / syrup BIB station. Unit has been leaking from the waste/water-bath overflow area and the main cooler section has reportedly been overheating. Photos show water pooling on the floor near the postmix rack. Engineer fitted a tube from the overflow/waste outlet to an empty catch container; this has reduced floor spillage but should be treated as a workaround unless overflow rate is confirmed normal. Please inspect: water bath level/fill, overflow/drain route, kinked or blocked waste tube, condenser cleanliness/airflow, condenser fan operation, compressor running temperature, ice-bank control/stat, soda recirculation pump/carbonator circuit, push-fit connectors and any split lines. Confirm whether the overflow discharge is normal or caused by overfill, blocked drain, overheating/ice-bank issue, or separate leak. Keep electrics dry and do not block overflow. Separate previous issue branch: this same Manchester postmix machine previously made loud knocking/rattling noises. Engineer found the internal condenser fan was loose and hitting the side/casing. If this noise returns, check fan blade clearance, fan guard, mounting screws/bracket, motor bearing, condenser cleanliness, and whether any casing/panel or external item is touching the fan area. Power off before close inspection. Separate postmix gun issue branch: the connected M4-style postmix gun had sticky buttons when pouring larger drinks such as Coke/soda. Buttons stayed down and drink would not shut off until pressed again several times. Staff tried warm soapy/sanitising water soak, soda-water flushing, and toothbrush/nozzle-brush cleaning. Fault persisted and engineer ultimately repaired/replaced the gun/head; currently working. If repeated, clean and flush first, then ask engineer to inspect button/butterfly plate binding, over-tightened screws, stem O-rings, valve plungers, springs, and whether replacement is required.