Isn't t a standard ts11 Robertshaw safety? Has a pilot line and thermocouple going to it? If that is the case it seems the thermostat is the problem. If you remove the 4 screws on the valve and remove the diaphragm,(for testing only)then you can test the flame. If it is still small bad thermostat. It is the same system they use in the 1930-1960 ranges. That is my specialty. You can get a rebuilt thermostat and or safety from Repco replacement parts in Texas for a lot less.