Put a catch pan undrr the belly below the case. There is a hole in the pan. take all the bolts out of the case, unplug the speed sensor plug. oil will drain out. cleam the case, 4 magnets on lower sprocket hub and check the chain tension. Bolt the cover back on as oring should be ok. Carefull not to overtighten the bolts ornthey will strip out. fill with chaincase oil from the dealer through breather plug and use the whole bottle. dont rely on the oil level plug. put the breather plug back in, plug in speedmsensor and ride.