Ah. I had thought that that diagram was for a different model.
No manual; the previous employee was apparently too busy stealing gas and taking tools home to do any maintenance on...well, anything, let alone the tractor. I'll see about requesting one for future projects.
The tin wasn't too bad to detach, fortunately I didn't have to disconnect the tach, just swung the whole thing aside. Pulling the top section of the steering column got me pieces of a blackened steel washer tinkling down onto the transmission housing. The locknut was indeed not locked; turning it down to its stop and bolting the steering column for a quick test found the steering working better, with less play. Still started catching a bit after a few turns back and forth, though, pretty sure that nut backed right back off. Tsk. Is staking the nut something you can describe, or am I going to need a manual for the visual aid?
I can't seem to find a washer in that area in the diagram, but it seems like it went between the locknut and spring washer...even with the nut at its stop, that line of components seemed a little loose. But then, the hydraulic block was just floating there, what with being unbolted, so maybe that's why. Still doesn't explain where these pieces came from...
The spring washer and whatever that is under it (#19) seem to be intact and fine. The #35 seal looks to be in good shape.
Though I really, really don't want to, I'll probably go ahead and mark the lines, disconnect them, and pull the block to see if it needs cleaned. So yes, if it isn't any trouble, pictures of where all the bits and pieces go after they inevitably fall all over the transmission and ground will probably be useful. I would guess that my habit of having parts left over after putting things back together would be a bad thing to exercise in this instance, heh.