1. The Dometic 24 is very, very old and the chances of getting much more life out of another one is somewhat remote. I took the same one out of my Hunter a year ago, (and installed a RM-2193 out of a wrecked slide-in camper) while it was still working, and person that bought it tells me that it lasted another 4 months before leaking out.
2. Before buying any used 3 way fridge
, unless it is priced so low that you can throw it away, be sure to see it working, at least on 120 volts.