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
RadiatorWater Pump Housing Disassembly
NOTICE
Do not damage the hole wall of the water pump
housing.
Insert a bar [A] into the pump housing [B], and hammer
evenly around the circumference of the mechanical seal
bottom [C].
Take the oil seal [A] out of the housing [B] with a hook [C].
...
Starter Clutch Assembly
Install the one-way clutch [A] to the driven gear.
Face the circlip side of the one-way clutch to inside.
Install the new snap ring [B] to the one-way clutch.
Install the drive gear [C] while turn it counterclockwise [D].
Apply molybdenum disulfide oil solution to the needle
bearing ...
Transmission Assy Removal
Remove:
Engine Sprocket (see Engine Sprocket Removal in the
Final Drive chapter)
Gear Position Switch (see Gear Position Switch Removal
in the Electrical System chapter)
Collar [A]
O-ring [B]
Remove:
Clutch (see Clutch Removal in the Clutch chapter)
Shift Shaft Assembly ...