I would say Camper Paul has it.. If it works in bypass. but not in automatic, and you have already replaced the thermistor twice.. Not much else left.
Check with dinosaur boards (Delete space add www. and .com) and see if they have one for it. If they do I will tell you what I found when I ordered one from American RV in California.
Mine is for an Atwood furnace.
First thing I notice out of the box was a general feeling of QUALITY, Nice big heavy traces, every solder joint looked pristine (And yes, I have the credentials to make that judgement), the board looked to be very well made.
Upon closer inspection (I have some engineering training however I never completed the degree) I found even the design was superior to the OEM board.
Made in the USA as well.
I highly recommend them.
Oh,, As for the furnace.. Since I slipped that board in it has failed one time.... I ran out of propane.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times