If any one of the parts is damaged, replace the mechanical seal as a unit.
Rubber Seal [A] Mechanical Seal [B]

Water Pump Housing Assembly
RadiatorFuel Tank and Cap Inspection
Visually inspect the gasket [A] on the tank cap for any
damage.
Replace the gasket if it is damaged.
Check to see if the water drain pipe [B] and fuel breather
pipe [C] in the tank are not clogged. Check the tank cap
breather also.
If they are clogged, remove the tank and drain it ...
Armature Inspection
Using the × 1 Ω hand tester range, measure the resistance
between any two commutator segments [A].
Special Tool - Hand Tester: 57001-1394
If there is a high resistance or no reading (∞) between any
two segments, a winding is open and the starter motor
must be replaced.
...
Torque and Locking Agent
The following tables list the tightening torque for the major fasteners
requiring use of a
non-permanent locking agent or silicone sealant etc.
Letters used in the “Remarks” column mean:
AL: Tighten the two clamp bolts alternately two times to ensure even tightening
torque.
G: Apply ...