iam rebuilding an old snapper rear engine rider and iam putting it back together and wher you adjust the belt I have the clamp tight, but when I lift the rear off the ground it spins on the shaft, it won't go in or out. just spins and I can't get the clamp tighter. ius this supposed to do this.if it on the ground it probully won't hurt it. just wondering if I forgot something on the shaft. I have a break down but it doesn't show anything. some of them had shims, this one didn't.