1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 194Get this manual
6Install new piston pin lock rings (e ach side of piston) using Lockring Tool (91-77109A1)7Make sure lockrings are properly se ated in piston grooves NOTE: Shaft of Lock ring Installation Tool 91-77109A1 must be modified (shortened) to 1.050 in(26.7 mm)1.050 in(26.7 mm)
CAUTION
Do not re-use piston pin lockringsUse only new lockrings and make sure they are properly seated in piston grooves
Piston Ring Installation