re the above you would be better to order a shaft and seal as a set
i changed my own recently and the wear on the shaft from a rubber seal was unbelievable
watch and make sure you line up the cross bar in the shaft with the space for it in the drive in the engine or you may break it or worse still damage the engine if it over heats
take the shaft off by taking off the brass cover on the front and then undoing the shaft making sure not to forget the washer
just make sure the the clutch cover is snug before you tighten up the allen bolts