I have 1989 4.3 L OMC I/O that is leaking oil from the lower unit. Oil drips out from around the prop. My questions are: 1) Cause. 2) Can it be cured by me, using a lower unit seal kit? The picture of the kit shows lots and lots of gaskets and seals, so I'm thinking it is for a complete strip down and rebuild. Is there something I can do short of that? Thanks.