the drive sprocket seal? you just drill a small hole in it not very deep is is only 1/4 of an inch thick. then screw in a screw with a flat end no pointed wood screws. don't do this near either edge. do it in the middle of the seal. screw in the screw and pull on it with pliars to pull the seal out. it will probably take a few try's and holes to get it right. be really careful not to hit the bearing behind the seal or the case with the drill bit or screw.make sure you pack the groove in the seal with grease before you install it. also make sure the mounting surface and the seal are clean on the outsides (no grease or oil) when you press the seal in. use a large socket or a piece of pipe to press the seal in all at once not one side at a time. hope this helps
