Thanks for the tips. I did find a video: https://youtube.com/playlist?list=PL66r7Hir5gawRxBChC8lwUyVi6_YRDFJO&si=-y6Ru0fBNi6y6pqX

Unscrew the unit’s exterior trim panel and you will see the furnace itself; there will be mounting screws that secure it to the surrounding framing or carpentry. There should also  be some visible 12V wires to disconnect and the propane line as well. Once all that is free, you yank away at the whole chassis and hope the exhaust pipe isn’t frozen to the ancient, rusty external vent!

That’s how I remember it anyway. 

I have the same issue with the same furnace. Any tips on how to access the motor/removing the furnace? 
 

thanks,

Marco

1990 Itasca Micro