Kenmore Ultra Wash series 600 or 700 with dribbling water inlet?

I have a Kenmore Ultra Wash dishwasher (series model 600 or 700 - not sure) that came with my home. It was purchased in December of 1990, and the nameplate says the model no. is 1660592. It has worked fine until this morning, when I found water leaking out the unit onto the floor. The unit was not running overnight, and after bailing out the bottom, I found that the source of water is what I believe to be the main water inlet, located on the left side of the unit, about 10 inches from the bottom. Water is slowly leaking out and filling the unit, so I either have to cycle the machine to drain it, or bail it out by hand.
I can't pull the unit out, because there is no slack in the Romex wire connected to the unit. I can see that the main copper water line runs to what looks like a solenoid controlled valve, which is connected to a rubber hose that connects to the main inlet on the left side.
Could it be that the solenoid valve has a deteriorated gasket? If so, can this be replaced inexpensively? What would you recommend? My short term solution is to disconnect the water and cap the tee connection feeding hot water to the unit (there is no shut-off valve to the unit). Of course, I won't be able to use the machine, but at least I won't be repeatedly draining it, either. Thanks for your feedback.