Trying to diagnose a Mercury 4hp-2stoke that misses during acceleration and always has since I owned it. Compression pegs out at 105 psi. Replaced plug, filter, carb, fuel pump, tank, hose, and ran three tanks of premium gas through it. I think the fuel system is good. Coil: Primary Winding Resistance- 00.8 milli ohms. Secondary Winding Resistance- 6.29 milli ohms. Used a pencil in the spark plug hole to bring the piston up to TDC. The mark on the fly wheel is about ¾ of an inch off the mark on the casing. Manual suggests that the fly wheel has been installed wrong (is that possible?), or that the key has been sheered off. The engine is only about 5 years old, starts on third pull, runs well at speed, and has never been run aground. Is sheering off the key common? That seems unlikely to me but I'm not a mechanic and don't have a fly wheel puller to check. Just looking for comments or ideas on how I should proceed. The closest Merc dealer is about 800 miles away so need to fix this bugger myself. Much thanks, in advance and all best for the holiday season. Bry