1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 233Get this manual
Gear Housing Reassembly IMPORTANT: The gear case assembly does not have any shims for the gear assembliesBacklash cannot be adjustedThe technician must verify that all bearing races are firmly seated in the gear case during reassembly and that all gear case components are in serviceable conditionPrior to installing the seal carrier and water pump assembly on the drive shaft, the FORWARD gear should be held stationary with screw driver or similar toolWhile pulling up on the drive shaft, lightly turn the shaft back and forthA light "clicking" sound should be heard indicating the presence of backlash between FORWARD and PINION gearsIf this backlash is not present, the pinion gear race andor forward gear race are not fully seatedRaces should be removed and inspected for debrisReinstall races and check backlashIf backlash is still not present, replace gear housing
aMandrel (91-817007)Seal