I had a Mercury that had a seal leak and I never had it repaired. Changed oil in it before every winter to keep it from freezing and busting. Never had a problem. Minor leak I'd say as when it was parked it didn't drip oil or showed any sign of a leak. Had that motor for over 20 yrs. Don't know how bad your leak is. Good luck with tearing that thing apart. Don't think I would want to try it manual or not. Trick to every trade