American Dish Service dishwasher holding water and barely dosing chemical — Ridgewood, NJ

The call

Two complaints from the kitchen, and they had been living with both for a while. The machine would not drain properly — water sat in the tub when it should have gone. And the chemical was barely arriving: detergent weak, rinse weaker.

What we found

A door-type dish machine is simpler than a household dishwasher, which is what makes it honest. Fill the tub, wash, drain, and three small pumps meter chemical into the cycle. When water will not leave, the drain valve is where you look; when chemical will not arrive, the tubing usually explains it long before anything electrical does.

The drain valve assembly had worn out. Its actuator and the linkage that lifts the valve are exposed to hot water and detergent every hour the kitchen is open, and it showed — the valve no longer seated or opened cleanly, so the tub emptied slowly or not at all.

The dispensers told the same story in a different material. These are peristaltic pumps: a roller squeezes a soft tube and walks the liquid along it, so the tube is a wear part by design, not by accident. All three had gone hard and flat where the roller runs. A tube in that state still looks fine from the outside and moves almost nothing.

The fix

Replaced the drain valve assembly with its linkage, and re-tubed all three dispensers — detergent, rinse and sanitiser — rather than the one that complained loudest. They wear at the same rate because they run the same hours, and coming back in a month for the second one helps nobody.

Then we ran the machine properly: fill, wash and drain through full cycles, watching the tub empty the way it should and checking that each line was drawing and delivering again.

Worth saying for anyone running a kitchen: dispenser tubing is a consumable, like a filter. A dish machine that washes but no longer doses looks like it is working, and that is exactly the problem — nothing on the panel tells you the chemical stopped arriving.