Dometic RM7732 fridge

I have a Dometic RM7732 fridge. It's 20 years old with it's second cooling unit and seems to cool ok. The upper board seems to be getting flaky. When I set it to level 3, it jumps back to level 1. Level 4 jumps to level 2. Needless to say, it may need replacing soon. I have a service manual but cannot seem to find a part number. Online searches seem to be useless for parts for this model. I found a board that did not have mine on the "fits these models" list. It looks the same but I'm uneasy about any ordering until I can get some verification. Directions??.....Suggestions??