Rwbanshee

Replaced seals in the motor. Put new tranny gears and shaft in because the threads for the front sprocket were stripped. And I guess the part I got was bad. I put the chain on and rocked it and it only shifted down once. Pulled clutch cover off and thought it could be the shift arm then I seen that it was stuck in 3rd. The adjustment screw seems fine. Anybody know what's going on?