Update: Replaced the lower oven thermostat. Everything running fine now. Had to pull out entire double oven from wall but I had a 4 wheel moving H-Dolly and some wood that I could stack up to just the right height allowing me to slide the unit onto the dolly. Didn't want to press my wife into service on this one. I rolled it out just enough for me to get behind and remove the old thermostat sensor wire and replace with the new one.
Wanted to do a professional job and make sure the new connections were low resistance nice and solid so bought a pair of ratcheting crimpers for the new crimp connectors I was using. I also heat shrinked all exposed metal on the connectors.
The only snag was that I bought the thermostat from the cheapest place I could get it online. It did come in an OEM GE factory box but when I went to screw the thermostat housing back into the oven faceplate the screws from the old thermostat would not screw in. When I examined the thermostat holes where the screws were to go in, I discovered that they were unthreaded. I mean completely smooth. I couldn't believe it, I had gotten this far only to be thwarted by a flaw in the part. Luckily I had a tap and die set and was able to thread the holes and get the screws to fit. I actually made a mistake on the first hole and tapped using the next size up. Luckily I had just the right length screw in my spare fastener box. I tapped the remaining hole with the right size and the original screw went right in. This is probably the third time I used that set but man it paid for itself on this one.
Oh yeah the other problem was the thermostat terminals were not labeled. I had taken pictures of the wiring before removing them so was able to determine where most of them went but for the two or three wires that had completely melted I did not know where they went.
I used the service manual sheet found inside the unit which had a nice schematic and description of operation. I used my multimeter and rotated the thermostat knob through all of the states of operation and was able to figure out thermostat terminal labels.
Used my bbg grill electronic thermometer and looks like it was working fine. Not sure how accurate it is supposed to be but when set to 350 and after about a 20 min steady state had been reached I got fluctuations -10 and +50 degrees F. The top oven, which uses a digital control mechanism was a little bit better giving -10 +20 degrees F so I figured the lower oven oil thermal expansion based thermostat fluctuations were probably good enough.