If there are notches worn into the splines, replace the sub clutch hub. Also, replace the steel plates if their teeth are damaged.

Clutch Housing Finger Inspection
Damper Cam InspectionWindshield and Other Plastic Parts
After washing use a soft cloth to
gently dry plastic parts. When dry,
treat the windshield, headlight lens,
and other nonpainted plastic parts with
an approved plastic cleaner/polisher
product.
NOTICE
Plastic parts may deteriorate
and break if they come in contact
with chemical substances
...
Hub Bearing Installation
Before installing the hub bearings, blow any dirt or foreign
particles out of the hub with compressed air to prevent
contamination of the bearings.
Replace the bearings with new ones.
Install the bearings by using the bearing driver set which
does not contact the bearing inner race.
...
Lubrication
Lubrication is necessary after riding
through rain or on wet roads, or any
time that the chain appears dry.
Use a lubricant for sealed chains to
prevent deterioration of chain seals. If
the chain is especially dirty, clean it
using a cleaner for sealed chains following
the instructions suppli ...