The short answer
On a Cove dishwasher that has been in service for years, poor cleaning is usually accumulated scale and grease on the arms and the tub, plus filtration that a rinse no longer clears. Descale and degrease the machine before you change how you load it, because on an older machine the machine itself is the variable that has changed.
What you are actually seeing
- Cleaning has declined steadily over a year or more — Means: on-page
- A dull film on the tub that does not wipe off easily — Means: on-page
- Spray arms feel stiff or wobble when spun by hand — Means: on-page
- Glasses have become permanently cloudy rather than spotted — Means: on-page
- Detergent is not fully dissolving in the dispenser — Means: on-page
- The tub still holds water at the end — Means: different-fault — Go to: cove-dishwasher-drainage-failure
- The tub is cold at the end of the cycle — Means: different-fault — Go to: cove-dishwasher-heating-failure
- Body: Match what you see before you take anything apart. Cleaning has declined steadily over a year or more. A dull film on the tub that does not wipe off easily. Spray arms feel stiff or wobble when spun by hand. Glasses have become permanently cloudy rather than spotted. Detergent is not fully dissolving in the dispenser. Some near-miss symptoms belong on a different page: The tub still holds water at the end points at a drain fault, covered on cove-dishwasher-drainage-failure; The tub is cold at the end of the cycle points at a heating or supply fault, covered on cove-dishwasher-heating-failure.
Causes, ranked for this machine
- Scale and grease coating the arms, the tub and the filtration — Why this rank: First on an older machine because the decline is gradual and scale narrows every jet at once rather than blocking one
- Filtration that is blinded rather than dirty — Why this rank: It can look clean and still be closed up, which is why an older machine benefits from a soak rather than a rinse
- A spray arm bearing that has worn, so the arm no longer runs true — Why this rank: An arm that wobbles sprays unevenly even with every jet clear
- A wash pump that has lost pressure with age — Why this rank: Explains a machine that is clean, correctly loaded and still washing weakly
- A rinse aid dispenser that is no longer metering correctly — Why this rank: Ranked here because it produces a dry result that has faded rather than failed
- Body: Ranked for a premium built-in dishwasher: hard-plumbed, on a dedicated supply, installed under a worktop by a fitter, quiet by design, with hand-cleaned filtration and a condensation dry that depends on rinse aid. Most likely: Scale and grease coating the arms, the tub and the filtration. First on an older machine because the decline is gradual and scale narrows every jet at once rather than blocking one. Next most likely: Filtration that is blinded rather than dirty. It can look clean and still be closed up, which is why an older machine benefits from a soak rather than a rinse. Third: A spray arm bearing that has worn, so the arm no longer runs true. An arm that wobbles sprays unevenly even with every jet clear. Fourth: A wash pump that has lost pressure with age. Explains a machine that is clean, correctly loaded and still washing weakly. Fifth: A rinse aid dispenser that is no longer metering correctly. Ranked here because it produces a dry result that has faded rather than failed.
What to check, in order
- Look at the tub and the arms for scale before touching the load
- Soak the filtration rather than rinsing it, and hold it to the light
- Spin each arm and feel for wobble or roughness at the bearing
- Check the rinse aid is actually being used between fills
- Body: Each check rules out the causes above it. First, look at the tub and the arms for scale before touching the load. Second, soak the filtration rather than rinsing it, and hold it to the light. Third, spin each arm and feel for wobble or roughness at the bearing. Fourth, check the rinse aid is actually being used between fills.
Checks you can safely make yourself
- Run the hottest cycle with a proprietary descaler and an empty machine, then look at the tub and the arms again — Tools: descaler — Time estimate: one long cycle
- Switch off at the breaker, remove the filtration and soak it in hot water with detergent before scrubbing and holding it to the light — Tools: bowl, brush, gloves — Time estimate: half an hour plus a soak
- Remove each spray arm where it lifts off, flush it and clear each jet with a cocktail stick — Tools: cocktail stick — Time estimate: half an hour
- Spin each arm on its mount and feel for wobble, roughness or side play — Tools: none — Time estimate: a few minutes
- Fill the rinse aid, mark the level and check after several cycles whether it is being consumed — Tools: rinse aid, notepad — Time estimate: several cycles
- Body: Checks an owner can make with the machine switched off at the breaker, or by watching a cycle. Step one: Run the hottest cycle with a proprietary descaler and an empty machine, then look at the tub and the arms again. Tools: descaler. Time: one long cycle. Step two: Switch off at the breaker, remove the filtration and soak it in hot water with detergent before scrubbing and holding it to the light. Tools: bowl, brush, gloves. Time: half an hour plus a soak. Step three: Remove each spray arm where it lifts off, flush it and clear each jet with a cocktail stick. Tools: cocktail stick. Time: half an hour. Step four: Spin each arm on its mount and feel for wobble, roughness or side play. Tools: none. Time: a few minutes. Step five: Fill the rinse aid, mark the level and check after several cycles whether it is being consumed. Tools: rinse aid, notepad. Time: several cycles.
Safety first
Safety
Switch off at the breaker before removing filtration, and wear gloves against broken glass. Do not open the door mid-cycle on a hot wash: the steam released is hot enough to scald. On a machine of this age, remember that the door carries a custom panel under spring tension set years ago: do not loosen door hardware, and treat any water reaching fitted cabinetry as urgent rather than cosmetic. Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. unplug-before-service
Where the owner fix ends
On an older machine, call a technician once it has been descaled and degreased, the filtration is genuinely clear, the arms turn true and washing is still weak. A wash pump or an arm bearing on a machine of this quality is a defined repair and normally worth making, given what replacing an integrated machine involves.
Nearest pages of the same kind
Generalized information
This page is generalized across the Cove dishwasher line. Fully integrated machines carrying a custom cabinet panel and machines with a finished front share the ranking above but not every part, and this page does not cover a specific model, control revision or installation. Family- and model-specific pages, where they exist, are linked below.
Links: - [Common COVE Dishwasher Problems](/blog/cove-dishwasher-problems) - [Cove Dishwasher: Abnormal Noise or Vibration](/blog/cove-dishwasher-abnormal-noise-2) - [Cove Dishwasher: Controls, Display or Error Code](/blog/cove-dishwasher-control-fault-2) - [Cove Dishwasher: Cycle Will Not Run or Complete](/blog/cove-dishwasher-cycle-fault-2)
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
