I have a portable maytag dishwasher model DWC 7400 AAW. It started only humming.The switch seemed to work and turn. It would fill ok with water, but the motor would not come on and the pump would not drain the water. A service guy said the motor was bad an not worth fixing. I did buy a used/rebuild motor and pump assembly and it did the same thing. I then bought a brand new motor and pump assembly and it did the same thing. I replaced the relay each time...What else???The power supply thing? Thanks