I have read that some people have replaced their Norcold 1210 with a Samsung RF197 (A Home refrigerator). I made note of it, but have not researched further. My Norcold 1210 was new last spring and has done a very good job retaining low temperatures. Much better than the old one it replaced.
When your temperatures go up a little, look at your fins in the top rear of the refrigerator. If all of the frost is gone, it defrosted itself. The temperatures will go down again when defrost cycle is done.