I've tried to fix a transmission in this condition before by ordering a new case half and taking it completely apart sending it off to the machine shop and having it hot tank.

The result was under deceleration it had a horrendous howling noise, it ended up being so annoying I just ended up getting a brand new transmission and doing the bearing mod, noise gone.

This is a definitely must do modification unless you're willing to gamble on a $2,600 transmission, that's right they went from 2100 to 2600 gotta love Polaris lol