Because I`m interested in this because I have a Attwood 2 stage furnace in my 5th as I said that I installed in 2015 , and had nothing else to do today , retired , I called Dometic who now owns attwood @574 264 2131 and asked what I would do if the furnace or stat was to go out and was told I would have to replace the furnace .Not good !
To be clear is your furnace the 2 stage type that in auto position will go into a lower fan and heat level if its within a few degrees of the stat setting ? Your stat looks like mine , its a Excalibur 8500 1V furnace . If so its run on 12v and it only works for that heater.
I saw a few of that type stats on e-bay and at one rv online store I guess might be old stock , or maybe it can be repaired by an electronic guru , its not a simple stat it has a circuit board and capacitors ....
Let us know what happens