My old Tappan gas oven would not maintain its temperature. It would light, heat up and then cool off. The oven burner would not reignite except on "Broil".

Because everything worked on "Broil" I deduced the thermostat was not working correctly as "Broil" essentially overrides the thermostat and turns the gas on all the time.

Now the oven will not light at all. The igniter gets red hot. It produces that hot odor if left on long enough.

What is my next step? It seems like the safety valve is defective, but why would that not show up until I replaced the thermostat?