I set the oven at 400F and hit bake. The model of oven I have automatically preheats, so I waited the 9 1/2 minutes that the oven requested and then took temperatures.
Left Thermometer - 300F
Center Thermometer - 295F
Right Thermometer - 250F
Not good. I decided to wait another 10 minutes and check the temperatures again.
Left Thermometer - 370F
Center Thermometer - 370F
Right Thermometer - 325F
I waited another 10 minutes and the results were the same. It looks like something is definitely off with the thermostat, it could need a simple recalibration, but more tests are needed first :(
I'm going to test it again at 300F to see if the thermostat is off by:
a) 30F which would mean a simple reset is in order or
b) Off by a different amount, which would mean the oven may need to be replaced.
Results will be forthcoming!