I need some help I can not figure out why my 500 is stuck in a gear and won’t come out or go in a new gear. This happened after I put a new piston in and checked everything on the bottom end. Everything look good not a hole lot of play. I have adjusted the clutch and it’s still stuck in gear and will not shift.

 

Probably a selector problem, are you sure you put everything back together properly when you "checked everything on the bottom end" You are going to have to take the cover off and check that selector mechanism anyway.