Old age? Blocked arteries?
Seriously, it could be that bits of the inner pipe that conducts the ammonia solution that cools the unit have rusted and broken off, and are floating around and lodging in parts they shouldn't.
Three things you can do:
- "Burp" the refer by disconnecting it, securing the loose parts, and rolling it. Yes, turning it over, and allowing things to settle, one side at a time.
- Buy a re-manufactured kit of all the innards that make it cool down, and install it. There are several manufacturers, people on here can give you their comments on that.
- Replace the refer completely. Pricey, but the only long-term solution
Hopefully, others will post even better advice. But it's not an easy situation to get out of, IMHO.
ps: I moved your thread to the correct sub-forum for you