While I'm on the subject of dumb things I've done with my roaster...
I've read that it's bad to let the MET get much over 600F in a Quest M3, but it's not clear to me exactly what the risks are.
I'm asking because during my last session somehow the heater duty cycle got stuck at 100% while I was doing other things (grinding a sample of the previous roast to check color), and MET got over 1000F before I smelled a bit of plastic in the air, realized what was happening, and turned off the heater. I let the roaster cool way down, then brought it back up to charge temp for another roast. It looked as though chaff dust on the walls of the drum was a bit charred, so I ran some seasoning beans through to clean it off. That seemed to work, so I proceeded with one more roast, which went OK.
I don't believe the temperature probes were seriously affected, though the relationship between MET and BT wasn't quite normal at the start and I had to wait for a while for the relationship to return to what it usually is (e.g., when MET idles at 475F in an empty roaster, BT=350F, etc.) As I've just torn down the roaster for a thorough cleaning, I plan to test the probes with ice water and boiling water to make sure they're OK, and recalibrate them in Artisan if needed.
I had painted the drum black with several coats of Char-Broil grill paint, properly baked. The overheating turned it into a completely white layer of ash that was still adhered to the outer surface of the drum but brushed off easily. The metal in some areas inside and outside the drum is slightly discolored (bluish-purplish) in places, particularly around the strut weld marks on the outside of the drum. The inside surface of the roaster is also slightly discolored near the elements, though it could be that it's always been that way. The copper tube I added for better airflow had some black paint deposited on it, which wiped off easily, and solder on a fitting I attached to it looks like it's been overheated -- grainy not smooth like it was when I did the solder job.
So... what sort of damage could have resulted from the overheating? What, if anything, should I look for?