GE profile not working

We have a GE profile spacemaker XL1800 that runs perfectly but does not heat the food. Someone suggested the magnatron which we got under warranty from GE and replaced. Still does not heat and says system error when the time is done. Any ideas?

Did they replace the diode along with the mag? If not, replace the diode and mag again. Check the cap for correct microfarads, I believe its around 1.5mf. Theck the door interlock micro switches.

Ardvaark