Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionRear Wheel Installation
Apply high-temperature grease to the grease seal lips.
Fit the collars on the both sides of the hub.
Left Side Collar [A]
Right Side Collar [B] (with Flange)
Engage the drive chain with the rear sprocket.
Install the caliper bracket [A] onto the stopper [B] of the
swingarm.
...
Oil Pump Installation
Install the outer rotor [A] into the crankcase.
Assemble:
Oil (Water) Pump Shaft [B]
Pin [C]
Inner Rotor [D]
To prevent dropping, apply grease to the pin.
Install the inner rotor assembly into the crankcase.
Fit the slot [E] onto the projection [F].
Replace the O-ring [A ...
Air Cleaner Housing Assembly
Install the ducts to the air cleaner housing.
Fit the projections [A] of the duct into the slits [B] on the
air cleaner housing.
Tighten the screws [A].
Torque - Air Cleaner Housing Duct Screws: 1.1 N·m (0.11
kgf·m, 10 in·lb)
Install:
Air Cleaner Gasket [A]
Duct [B] ...