replaced the oven safety valve. This device uses heat from the pilot to hold open a valve that allows gas from the thermostat control to feed the main burner. It works by boiling the liquid mercury in the sensor bulb, producing the pressure to hold open the valve. My sensor had failed from old age, leaking the mercury.
Spilled mercury needed to be collected and properly disposed, and the valve was a tough fit among the sheet metal parts that form the path for the gas to the burner slots. The valve is secured by flat head sheet metal screws and the gas plumbing is a tapered pipe fitting. The sensor bulb has a small steel spring to hold it in the proper spot to sense the pilot light.
I used gas-rated pipe dope on the gas fitting, probably unnecessarily. Valve faces only 1/2 psi pressure...