I have never opened a microwave, and this doesn't seem like the occasion to start. Considering that I can get a good new unit for $250-350, it doesn't seem worth the effort to repair this one. I'll take some time to shop around because we are still getting some heating from the unit. I wonder why this was designed with a complicated PCB instead of a transformer. I guess a robot could crank out the PCB at less cost. Oh well, I guess it doesn't matter. Thanks for your advice.