Fire inside DACOR DMT2420

I purchased a DACOR DMT2420 in May 2003. It worked fine for a couple years, but yesterday, the waveguide cover inside the unit caught fire! The waveguide cover is a silvered piece of cardboard (often made of mica in other microwaves). Now I have to navigate the world of appliance parts looking for what looks like a 50 cent part (which are usually impossible to find).

I found a waveguide cover ($9) at Reliable Parts in Sacramento and replaced it. However, the unit still caught fire. Not a plus for kitchen appliances in my view, and not acceptable for $400+ microwave.

Also, shortly after buying and installing the unit, the door would not open and had to be repaired.