Mercury Mariner 30/40 4-Stroke Outboard Service Manual 1998, Page 314Get this manual
POWER TRIM
8Inspect check valve for debris; clean debris from check valve if foundIf debris cannot be cleaned from check valvereplace shock piston as an assembly9Clean shock and components with compressed air10Remove inner a-ring from shock rod piston51199
aShock Pi stonO-ring 11 Remove cylinder end cap assembly from shock rod12Inspect shockIf wiper (located in cap) has failed to keep rod cleanreplace wiper13Place end cap on clean work surface14Remove rod wiper, inner a-ring, and outer a-ring