HELLO: Heres an idea, place the quad up on a milk crate or up on your quad jack. Now, will trying to rotate the rear tires try to shift it in to all the other gears and see what happens, your problem my be the engagement of the shift shaft to the shift drum, what Im talking about it the end of your shift shaft my be damaged, if so or you think it is youll have to break the case apart to repair. check with an online manual or go to BIKE BANDIT and check it out on their OEM parts fich. GOOD LUCK... GREASY. LET US KNOW WHAT YOU FOUND.