Mercury Force 9.9, 15HP Outboards Service Manual, Page 65Get this manual
5Remove flywheel key (A) DINSPECTING FLYWHEEL
1Inspect flywheel fo cracks and breaks
WARNING Cracked or ch ipped flywheels must be replaced At high engi ne RPM damaged flywheel can fly apart, throwing metal fragments over large area2Inspect taper in bore of flywheel