My 20 year old "Cold Machine" did not work when I bought the boat last year.
I took a 110v compressor off of a mini fridge and brazed it in place. It works great. Keeps the fridge cold when on shore power and draws 100 watts off my inverter.
It also is R134a, the Cold Machine was R12, so I can recharge it with off the shelf coolant.
Cheaper than an $800 replacement unit.