Mercury Mariner Outboards 2.2 / 2.5 / 3.0 Service Shop Manual, Page 59Get this manual
Pinion Gear and Drive Shaft Removal 11 Remove clip (a) from end of drive shaft using screwdriver
12Pull drive shaft (a) out of housing, taking care not to drop pinion gear (b) Remove pinion gear from housing
Replace shaft ifshaft seal surface is deeply groovedallowing water to enter gear housing shaft splines are twisted or worn