Hope this is in the right forum category...
Have a early 90's GTI gas fireplace (off shoot of heat and glo). Wall switch has never worked with this unit so just used the on/off rocker switch behind the access panel to make due. Unit was started this winter and the switch no longer will do anything. The pilot flame lights and stays lit. Replaced the thermopile just to make sure it wasnt that and still having the same issue. Dug a little deeper and thought maybe the rocker switch was bad (maybe that was what was causing the wall switch not to work to?). Bought one of those installed it with the black lead from terminal "A" to the "C" position double tap on the switch, that did not do it so I tried position "D" as well to no avail (cant remember which side it came off of when unhooked from the original switch, pretty sure it was the upper lead on the pic).
Can jumper the top lead on the valve assembly (red terminals in pic, lead "A") to the gas valve lead "B" and the flame will come on. Thought maybe one could just bypass the rocker switch and hook it directly to the wall switch but when the pilot flame was blown out the gas supply did not shut off so for safetys sake dont want to go that route. So basically back at square one with a new thermopile and on/off switch installed. Anyone have any ideas as to what may cause the flame to not turn on? Seems to me it would be something simple as the gas valve is working and the thermopile is working.