I bought a good looking 246 in a saw junk pile. I thought it was seized but the top end and bearings are fine. It looks like somebody changed the clutch drum from the star type to the rimmed sprocket type and it doesn't fit into the plastic worm gear wheel on the oil pump. The clutch binds up on the cover. Does anybody know if I can change just the plastic wheel and where to find one? The drum checks out for a later 246. Thanks