904 seal and o-ring replacement

If it is the input shaft lever then you may have to pop the seal out from the inside. I have the same leak (I think) on mine. i saw a tool a ways back that can be used to replace the seal, but there is not much room to work in there.

As far as the o ring on the NS switch, probably just as easy to replace the switch. That is what I did. The switch was like $10, and the O-ring is not listed anywhere for easy replacement.