Surprisingly cheap, yes, and worth every penny. I've replaced three on this particular lever in less than six months. Deere warrantied them, but that doesn't solve the issue.
Enough about that. So there could be water in the chamber below the ball where the lever pivots, and it wouldn't necessarily drain into the transmission? That makes for a good possibility here. I guess that's where I should go next. That's just a standard snap ring with two holes in it? Not one of those tricky ones with no ears on it and no way to get under it?