For the last few months I have been running a 25 T-1 on my motor. Everything is fine with it. I decided to bolt on a 27 T-1 that is also fairly new, that I ran maybe 20 hours last year. When I turn the 27 the front of it seems to rub on the gearcase. I put the 25 back on and dont have any problems with it rubbing. What would cause one to rub and not the other? Is it possible that my thrust washer has worn?