Today s oil will dissolve much of the carbon left in the power head from the junk oil they had in the past. I suspect your running an excessive amount of oil, (IMO) and as most of the oil doesn’t get burned, your motor will ooze a lot of it. If you’re still using a original coil, with all the original wiring, be sure to take a pair of oars along with you. If the wiring on your coil is so good its worth preserving, then save it for display. Build one with all new components for running the motor.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.