Got this transmission in from a friend because it was puking oil all over the place. The previous owner also liked to use a screwdriver or chisle to get the old seals out so the case is beat up pretty bad.
Upon inspection the mainshaft seal was never installed correctly by the previous installer. As you can see it was in cock eyed and not pressed in to the correct depth.
Removing the old seal
I found that they did not install the inner cork seal either and used a single lip seal. I got the cork seal and a duo seal to put back in.
After putting a little yamabond around the seal to help fill the chunks missing from the seal ring I pressed the new seal in to the correct depth.