Has anyone ever replaced the seal on the (output)counter-shaft without removing the engine and spitting the cases? If so, what problems could I encounter, tips, tricks? I have to replace the shift-shaft seal too, but that looks pretty easy.

Nobody has tried this!!????
Guess I'll have to be my own guinea pig. If it works, I'll post a "How to", but it may be later in the winter.

I was waiting,,,I think the seal can be pulled without spliting the cases. Pull the sproket and the sleeve and the seal will come out. I vagely remember a ring around the seal, but without looking can't be sure.

I will, but may be a few days..Sorry. I will try to before I leave.

Thanks, Stan. There is no hurry.
Didn't know that sleeve was easily removable. I thought it was "pressed" onto the output shaft.