Help on Oliver 77 Diesel

Excessive carbon would indicate incomplete combustion. You can safely assume that the pump puts out the same amount of fuel in each cylinder, and unless the injector nozzle was putting out a bad spray pattern, you are left with low compression as a factor in the incomplete combustion. If the piston pin (or the wrist pin boss in the piston) was worn, it means that the piston was probably not achieving proper compression compared to the other pistons; OR there was another factor such as a bad valve or leaky head gasket, or bad rings which resulted in weak compression in #1. And the blocked exhaust port will accelerate the process of carbon buildup because the cylinder will not breathe properly.
I wouldn't speculate on whether the compression problem caused the wrist pin condition or not, but I suppose if there was near ZERO compression in that cylinder, that there would be forces rapidly alternating between compression and vacuum which you would not normally see on the piston and might cause 'hammering'(for lack of a better word) on the pin and bushings. If that was true, you might also see similar wear on the bottom half of the rod bearing, which did not appear on the other cylinders rod bearings.
I would be interested in what others think...