2001 Mercury Mariner 50-60HP Factory Service Manual, Page 429Get this manual
NON-BIGFOOT GEAR HOUSING
NOTE: Remove any burrs or sharp edges on the shift shaft splines before removing the shift shaft bushing4Remove shift shaft bushing and "E" clip from shift shaftReplace shift shaft if splines are twisted or damaged on either end of shaftRemove (and discard) O-ring if damaged