Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 208Get this manual
GEAR HOUSING
4Lubricate ball bearing with Quicksilver Gear LubeRotate inner bearing raceBearing should have smooth actionIf ball bearing sounds or feels rough or has catches, remove and discard bearingRefer to "Disassembly" preceding
NEEDLE BEARING 1Clean needle bearings in solvent and dry with compressed air2Replace bearing if needles are rusted, fractured, worn, galled badly, discolored, or if area of shaft that bearing contacts is worn or pittedRefer to "Drive Shaft" following