To reply to my own post, and bump it to request review from the APP team. I have checked all the connections, checked (to the extent I could with an ohmmeter) all the parts. I have a 5 month old magnetron, new diode, new capacitor. Still no heat
I suspected the switches, but while I have noticed that the light does not dim and the characteristic hum doesn't seem to happen, the magnetron housing and heat fins still get hot. This suggests that the switches are not locking out power to the magnetron. But again, the water in the mug inside the microwave does not get hot.
Could it be a switch? Any ideas?