Hardening, shrinkage, or damage of both gaskets and O-rings after disassembly can reduce sealing performance.
Remove old gaskets and clean the sealing surfaces thoroughly so that no gasket material or other material remains.
Install the new gaskets and replace the used O-rings when re-assembling.

Force
Liquid Gasket, Non-permanent Locking AgentCommutator Cleaning and Inspection
Clean the metallic debris off the between commutator
segments [A].
NOTE
Do not use emery or sand paper on the commutator.
Check the commutator for damage or abnormal wear.
Replace the starter motor with a new one if there is any
damage or wear.
Visually inspect the commutato ...
Clutch Plate, Wear, Damage Inspection
Visually inspect the friction and steel plates for signs of
seizure, overheating (discoloration), or uneven wear.
Measure the thickness of each friction plate [A] at several
points.
If any plates show signs of damage, or if they have worn
past the service limit, replace them with new on ...
Water Pump Housing Assembly
NOTICE
Do not reuse the mechanical seal and oil seal.
Apply high-temperature grease to the new oil seal lips [A].
Press the new oil seal into the housing with a bearing
driver [B] until it stops at the bottom surface [C] of the
housing.
Special Tool - Bearing Driver Set: 57001-1129
...