have got to replace the front sprocket seal on the young fellas 82 xl250.did it a little while ago but buggered the seal putting it in so going to have to do it again.last time had the motor out and loosened off the lower 1/2 of crankcse and tapped the seal in put it back together but it leaked around the out side of the seal.i guess that you must have to lower the shaft from the top 1/2 of the crankcase as well? is this correct?i dont want to have to do it again any help would be apprecieated.cheers gregg