Dishwasher began making a loud grinding / vibrating noise during the wash cycle. Due to the age of the unit I replaced the complete lower assembly sans drain pump and water temperature thermocouple. Reinstalled the unit and the noise is still there! Could it be the water supply valve solenoid not seating properly? As far as parts go I'm thinking there is only the drain pump and electronic control panel remaining (not counting the internal arms, etc.) and I don't see how that could be a problem. What am I overlooking?

Thanks