We have a late 1960's Kitchenaid Superba (by Hobart) dishwasher.
Problem: the drain operates continuously, so the dishwasher can never fill with water. (The water comes in, but it's immediately pumped out.)
Never had this problem until I tried one of the cycles that I don't regularly use. As soon as I pushed the button to start it, the problem appeared. Makes me suspect something went wrong in the control unit.
Is there an easy way to tell whether the issue is with the control/timer unit (maybe an electrical issue is keeping the drain gate open?) versus a problem with the drain solenoid/gate itself?
Replacement parts aren't cheap, so I'm hoping to narrow down the problem.
Best Answer
Answer is in the comments to the OP, based on suggestions given there.
Summary (but note that I may be calling some things by an incorrect name!):
[Note - I'm omitting all the other steps I took, when I was originally suspected that the controller unit was the problem. I still don't know what I did that originally caused that piece of glass to get dislodged from wherever it had been sitting for however many years, and get stuck in the drain valve. But the fact that I tried running a cycle that I had never used before seems to be ... unrelated. Or at least, I can't figure out the relation. It seems to be just a bizarre coincidence.]