I was cooking a bag of popcorn and my GE Profile microwave began making an arcing noise and smoking. I turned the micro off immediately and after a bit of googling, determined the magnetron had gone out. I ordered the correct magnetron and diode from appliancepartpros.com and disassembled the microwave yesterday to replace the parts. I noticed immediately, that the outside of the small dome above the magnetron was scorched rather severely and the inside of the waveguard where the magnetron inserts into was scorched brown, as well. The magnetron antenna was melted substantially and I guess had arced into the dome part of the waveguard where it inserts. I've tried to attach plenty of pics so you can easily see what I'm talking about.

My question is, is this even repairable? I'm assuming I would need to sand the area in the waveguard where the magnetron inserts and re-paint with appliance paint, or the new magnetron will arc out in the same area. Or would it still short out even if the area is sanded and re-painted. It's a fairly small hole to try and do much sanding and painting inside but I guess it could be done. Has anyone ever seen this particular model with this same problem and was it fixable after that much damage from the arcing. Thanks for your help!