1988-1992 Mercury Force 5HP Outboards Service Manual, Page 203Get this manual
c REMOVING GEAR HOUSING
A WARNING
Always disconnect spark plug lead to prevent accidental starting of motor1Drain gear housing Remove drain plug and washer (A) from starboard side of gear housingRemovevent" screw and washer (8) Drain gear housing grease into suitable container, oz(0.12 L) capacity or greaterProbe drained gear lube with magnetSteel shavings indicate possible abnormal wear in gears or shifting mechanismLopsely reinstall drain plug with washer and "vent" screw with washer