Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionLubrication
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 ...
Liquid Gasket, Non-permanent Locking Agent
For applications that require Liquid Gasket or a
Non-permanent Locking Agent, clean the surfaces so
that no oil residue remains before applying liquid gasket or
non-permanent locking agent. Do not apply them excessively.
Excessive application can clog oil passages and
cause serious damage.
...
Rear Shock Absorber Inspection
Remove the rear shock absorber (see Rear Shock Absorber
Removal).
Visually inspect the following items.
Smooth Stroke
Oil Leakage
Crack or Dent
If there is any damage to the rear shock absorber, replace
it.
Visually inspect the rubber bushing [A].
If it show any signs o ...