Maytag MDBTT79AWW dishwasher fills and nothing else. Once filled you hear a click, followed by a humming sound for 3-5 seconds, then silence. This will happen two or three more times, and then unit will shut off. Motor doesn't start. Repairman says he thinks control board is bad, but he sounds like he is guessing. I performed a field service test , which indicated a fault in the high current motor circuit. Unit is seven years old. Don't know whether to attempt repair, or replace.