Just to close the loop, the winner is ..... oil in the #2 cylinder! Removing the glow plugs is definitely the way to go, it's a lot easier than messing with the injectors. Once I got them out I cranked it over, it blew a geyser of oil out #2. I let it sit for a couple of minutes and did it again, lo and behold another geyser of oil shot out. Cleaned off the glow plug and reassembled, and it fired right up on the first try. I'm happy again.
On a side note, the engine has a bracket for a "pressure reduction mechanism," and the lever and return spring is there. When you push it, though, it doesn't feel like it's actuating anything (and it certainly didn't help me clear the oil). I wonder if the rest of the mechanism isn't installed. It's listed in the parts diagram for the engine.
THIS ... Now I just need to devise a way to keep this from happening the next time I change the oil. ... Has anyone heard of any other ideas to prevent this other than pouring slowly???
Curious because I need to change the oil on my Jinma 284.