Last season on my 00 YZ426f my chain started jumping around, so I changed the chain (did X ring) its what i always run. That wasnt it. So i changed my front sproket, still jumping.(only when you re lugging the engine, not under load.) The back sproket looks good still. Also changed the chain block to BRP full plastic type. When I had my chain off and in gear, you could move the front sproket about a 1/4 turn before it lashed with the gear. Hoping the tranny isnt gone. Anyone else experience this?