If any is worn down to the service limit, replace the brush assy.
Starter Motor Brush Length [B] Standard: 12.05 mm (0.4744 in.) Service Limit: 6.55 mm (0.258 in.)

Starter Motor Assembly
Commutator Cleaning and InspectionExploded View
AL: Tighten the two clamp bolts alternately two times to ensure even
tightening torque.
G: Apply grease.
R: Replacement Parts
G: Apply grease.
L: Apply a non-permanent locking agent.
R: Replacement Parts
Specifications
...
Immobilizer Amplifier Replacement
Remove the upper fairing assembly (see Upper Fairing
Assembly Removal in the Frame chapter).
Disconnect the connector [A].
Pull out the immobilizer amplifier [B] together with the rubber
protector [C] from the air intake duct [D].
ECU Replacement
Refer to the ECU Removal/Instal ...
Front Fork Inspection
Holding the brake lever, pump the
front fork up and down several times
to inspect smooth stroke.
Visually inspect the front fork for oil
leakage, scoring or scratches on the
outer surface of the inner tube.
If any doubt about the front fork, it
should be checked by an authorized
K ...