I am repairing my son's '07 450F,and replacing a couple of gears. I am trying to fit the 5'th gear wheel(new) onto the shaft. It meshes w/ the 3'rd gear wheel(also new). The gear only slides on so far,then it will bind.the old gears work fine,so I don't think it is the shaft.Is there some trick I am missing?Perhaps use lapping compound? Otherwise,I am going to send it back,and have to wait another week or 2 for a replacement.