See some of the FrigoBoat threads with Flying Pig, keel coolers (not the problem/failure, but might have been a contributor), and capillary tubes.
It may be beyond help, but if you're getting cool, but not cold, it's probably not a clog (actual clog will kill cooling
cuz no gas moves).
If you can revive it, the next step would be to add a filter-dryer and filter such as FB claims are now included to solve the problem of the only such in the original being right next to that lovely hot compressor, defeating it.
Adding gas isn't rocket science, fortunately, and aside from not having one, neither is vacuuming and starting over (I did it many times before proving it dead at great expense).
to the keel cooler should have no impact on the potential for failure, I wouldn't think. There are some reports of KC failure through the sintered bronze block, but mine took somewhere between 3-5000 impacts in our wreck and kept on doing the job for the rest of the time we owned it before the system packed in due to an irremediable clog (cap tube just like the suggestions you've been hearing), so I can't imagine the electrolysis
issues of the instant cases; my maxprop zinc (big, heavy, dome, not a tiny thing like the KC zincs, of which I didn't have one) disappears every single
month, and I didn't have a KC failure in the 8 years it was on...
Richard Kollmann has LOTS of history
on these units; the US distributor is a participant in CF; he's Rob, known as Frigoboat Info here, and he went FAR out of his way to assist in our attempts to save the system.
It failed, but not due to cooling issues, and since I couldn't replace the evaporator without tearing my reefer out (I put it in before the top wen ton as I was building it), I had to go to something different.
If I could have, and MAYBE, even, at the nuisance value and effort involved, given how much the new one cost, and how it works just fine other than it requires water AND air cooling to keep the same cold, at literally double the cost in electrons, I would have gone back with the identical system, but with proper filter-dryer and filtering in place to prevent a recurrence of the problem (a hard-stuck clog in the cap tube, immobile despite nitro pressure one way and vac suck the other in both directions, while heating
the cap tube, as well as evident deterioration of the oil
- a different problem, but maybe the root of the issue).
I hope you get it resolved. If I could have replace the entire system (not tearing out the box), I would have done, and vastly preferred, that.