Lobster wrote:
Have been trying to work out why our dishwasher is no longer cleaning
properly (a 5-yr-old Bosch built-in; can't find a model number).
Basically, stuff on the top rack, and sometimes on the bottom one,
invariably comes out with gritty residue stuck all over it. Things I've
tried out/checked:

- Ensured spray holes in rotor arms aren't blocked;
- Cleaned filter in bottom of machine;
- Opened door mid-cycle to check rotor arms move (but can't tell how
vigourously though)
- Changed detergent (we're in a soft water area so no need for softener)

During the wash, water reaches the upper rotor via a flat grey conduit
attached to the inside of the machine, and which mates up at the back of
the upper rack with an aperture leading to the upper rotor; I'm guessing
that for whatever reason not enough water is getting through? How can I
tell?

What I would do, is to put two identical bowls open side up. One on the
bottom shelf and the other on the top one. run the machine on a rinse
for a predetermined time. The bowl on the bottom should have about twice
the amount of water in it that the top one has.

Logic being, the lower bowl will collect water from top and bottom spray
nozzles, where as the top one will only get water from the top spray.

One thing I've noticed is that after a cycle, if you lift the filter the
water in the machine's sump is really mucky; is that normal or should it
be basically clean 'rinse' water down there?

I would expect that to be clean cold water. The last thing a dish washer
does, is to take on board cold water. This helps the drying cycle by
condensing the steam/water onto the base of the dish washer.

Dave