I've had this Whirlpool 1200 dishwasher for about 6 yrs now.
Every couple years it eats an impeller/chopper and I've gotten pretty
good at tearing it down & replacing the thing.
A couple months ago it started a new problem. Every once in a while
there would be [pretty clean] water standing in the dishwasher at the
end of the cycle. [i leave them in over night- it was there in the
morning]
Nothing was leaking so I figured it must be the drain pump- as the
overflow was working somehow. So I got a new pump and all was well
for a while.
Next time there was water standing in it I tried blowing back through
the hose where the drain goes into the disposal. Bubbles came up
in the dishwasher- and it drained when I hit the cancel button.
A couple weeks later it clogged again. This time I thought I'd try to
suck the clog through the pipes. Hooked shop vac to drain at
disposal- tried to suck for a couple minutes. It wouldn't budge. But
I could still blow into that pipe with just a couple pounds pressure
and clear the clog.
Now it is leaking out a little bit during the cycle. Sometimes it
seems to clear itself- as I'll have a puddle, but the drain will be
working by the end of the cycle.
Other times it dumps a quart or so of water on the floor. Sometimes clear- asometimes dirty.
Through all this it seems to be washing the dishes well- glasses and
silverware are rarely spotted.
Any thoughts on where to look?
Thanks,
Jim

Looks like it comes around the left side of the door when the overfill quits working.

Sorry about the model number-- I put an extra 'T' in there- should be GU1200XTLTO.

Jim

Thanks Gene-
I just cured it[?] today.

Seems it was 2 problems. The intermittant clog was the little rubber flapper of the check valve that had come apart-
Model GU1200XTLT0
part number 5 on the pump and motor parts diagram [Part Number: AP3152971 ]
I tore things down to where I could see the inlets to both pumps and ran 3 cycles before it clogged again. Then I blew like hell on the drain hose back towards the dishwasher, and the little rubber disk appeared.

The leak seems to be a bad door seal as I don't get any standing water now- but it still leaks & it is definately around the door. Parts about $20 apiece.

I'll know for sure next week- but I think life is good.
Jim