It's interesting how many sailboat diesels I see that are dead or require a rebuild at <2k hours. To me, this suggests poor maintenance. Properly maintained, these engines should easily go 4-6k hours or more before requiring a rebuild. Before tearing into any diesel, and especially one with expensive or difficult to obtain parts, I'd be looking at replacing all filters and fluids, checking injectors, fuel lines and tank, and doing a compression test (testers are cheap online). If the engine runs, but not well, often running a can of Lubro Moly Diesel Purge through the fuel system will clean things up - run the engine directly from the can for best effect.
Diesels are very simple, needing only compression and fuel to run (injection timing and spray pattern are important for good running, but I've seen them run with both in far less than ideal conditions).