I bought a used CRF230 and I've just removed the chain. I notice that the sprocket is loose. It wiggles from side to side or counterclockwise and clockwise. Its like the square teeth on the sprocket are worn. Is this normal? The sprocket doesn't seem to be in danger of coming off. The other thing that I've noticed is that the bolts that hold on the sprocket have different size heads. One is 10 mm and one is smaller (8 or 9?) Is this normal or was the small one stripped and replaced? .