Hi, I have a older (15+years) cozy direct vent gas wall heater with the original manual thermostat wall control (2 wire).

Last year, the gas valve was replaced after replacing multiple thermopiles ( pilot would go out).

Its been working fine until last week- the pilot stays on but the gas valve doesn't "open" unless I give the valve a little whack. then the gas valve will be responsive to the thermostat for a bit then non responsive after.

I tested the thermostat with a jumper cable- no response
I tested the TH TH/TP on the gas valve with a jumper cable- fired up and then right after tested the thermostat- it fired up.

Is the issue a faulty gas valve, faulty wire or thermostat?

I hope the issue isn't the gas valve it was expensive to replace.