I pulled the gearcase off because the only unpleasant sound I heard was coming from the water pump. I wanted to check that. I pulled the flywheel off the first time to clean the armature. Ants had made a home there. I pulled it the second time because I read about the sensor coming loose and throwing the timing off, so I checked that. The third time I pulled it off because it was firing way out of sync, that was when I found the woodruff key was sheared off, and then today because I noticed it move real slow on crank and suddenly speeded up I assumed I sheared another key,and I was correct. You have to understand this motor was sitting in bushes for six years. Ant and cockroaches had infested many parts of it. Its amazing it ran at all. When I removed the lower unit three of the bolts sheared off. I had to drill out those and retap and put in helicoil. It seems to you that I am jumping around doing things crazy but in reality Ive been following everyones advice. and doing things in a methodical order. I had electrical prob to sort out, then when I followed the manual for setting slow speed needle valve the manual setting was wrong, it finally started running good then blew a head gasket. because I let it go low on water in the tank i have.