Hi I just prchased a 15' side console sunbird (fixer upper) for fishing. I'm pretty mechanically inclined but have never worked on an outboard. first thing Inotice was a grease comming out around the prop I'm sure there must be a shaft seal ther wondering how hard it is to replace and if there are any special tools required? Also what is the pupose of the scag on the bottom of the lower unit, this one is broken not completly gone maybe 1/2, what affect will this have and is there a fix.