The bake element in my 1960s Westinghouse wall oven suddenly will only heat up to about 200 degrees. This oven is an odd size, wider than it is tall, so replacing it is not an option without remodeling the kitchen. I first thought the bake receptacle was at fault, both the ceramic shell and metal contact were broken on one side, and the tab on the element was rusted on that side. I replaced the receptacle, sanded the tab clean with a wire wheel and reinstalled everything, still not getting up to full heat. Then I got out the multi meter and took measurements. I need to know whether the thermostat is bad (I hope not, they are rare and expensive) or whether one of the wires between the thermostat and element has a break.

With both probes plugged into the bake receptacle and OVEN on, 120v.

Back of thermostat measurements (thermostat is OEM # 5300162224, or RobertShaw replacement 5450-224):

Main power input tab (#1) to main ground tab (#5): 120v
Main power input tab(#2) to main ground tab (#5): 120v
Bake tab (#6) to element ground tab (#4) with OVEN on: 240v
Broil tab (#7) to element ground tab (#4) with OVEN on: 120v
Bake tab (#6) to element ground tab (#4) with BROIL on: 0 v
Broil tab (#7) to element ground tab (#4) with BROIL on: 240v

Currently neither of the 2 elements gets fully hot, they went out at the same time, but I assume that's because they share a common ground - I've NEVER had a problem with the broil element, and never had to replace it.