One of the first things we did when we got the boat to Oregon was have the yard replace the seal on the prop shaft. This is the stuffing box, where the prop shaft exits the hull. The seal was fine for some time, then started leaking. We thought this might be the nature of the seal, we learned how to adjust the gland nut and the drip stopped.
After a good nights sleep the idea of the drive train alignment emerged. A misaligned prop shaft would contribute to early seal failure.
So more research, reading old .pdf downloads, and just gut feelings, lead to checking the engine alignment by disconnected the shaft at the flange and measuring distances around the flange. It was about .002 inch off, the aft part of the engine was low.
So looking at raising the engine using the aft mounts, we found the port side mount was actually broken in two.
After a few calls, we found a local fabricator who could repair the mount. The plan was to weld it back together, and add a gusset for strength. The hourly rate was $75 and he quoted about an hour.
After reinstalling the mount and finishing the alignment, the engine was run for a few minutes with the shaft turning. . . . . No Leaks!
It all turned out ok. We looked at the other mounts, the starboard aft mount was repaired this same way some time in the past.
Boat yoga is good exercise.