Im replacing my cam chain for the 1st time on this bike, 06 yz450 cause it started to make a noise when reving up in the chain area. Bike still ran great, valves are in spec.....When I got to the flywheel gave it a little tug before putting on the puller and it slipped right off. Fits tight when all the way on, just slips on and off easy. Do I have a problem here??? Any help would be appreciated.