1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 233Get this manual
GEAR HOUSING
5Inspect bushing surfaces of propeller shaft for pitting or wearReplace shaft and corresponding bushing if wear or pitting is observed6Replace shaft if any of the following exist: aSplines are twisted or wornbOil seal surface is groovedcShaft has noticeable wobble or is bent more than 0.15mm (.006 in
aBushing surfacesOil seal surfaceMeasure here for wobble (When measuring shaft for wobble, use v-blocks and support at bushing surface)
Water Pump, Drive Shaft and Shift Shaft
1Remove bolts from pump cover2Remove cover, nylon washers above and below impeller, impeller and drive key from drive shaft3It is recommended that impeller be replaced whenever gearcase is being serviced