Sounds like it's time to flip it over and take the bottom off. It's not too hard to do.
1) drain and remove all the racks
2) disconnect the circuit board connections - the connectors are all different
3) flip it over and remove the screws holding the bottom on
4) lift the bottom up from the front - the fan in the back will still be connected I think it has a connector as well but you can just tip the bottom to expose all the plumbing.
I can post some pictures tomorrow if that would help. I also have the parts and service manual if the would help. They don't really contain much info beyond the obvious.
If you don't feel up to it maybe your idea about a dishwasher repair guy might work. Maybe check local collages to see if they have any ideas. They might have had one in a darkroom once upon a time.
--- look like Mike beat me to the post