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 InspectionWheel Alignment Inspection
Check that the notch [A] on the alignment indicator [B]
aligns with the same swingarm mark or position [C] that
the other side alignment indicator notch aligns with.
If they do not, adjust the chain slack and align the wheel
alignment (see Drive Chain Slack Adjustment).
NOTE
Wheel align ...
Starter Motor Assembly
Install the positive brush assy [A] and the starter motor
terminal [B] as shown in the figure.
Replace the O-ring [C] with a new one, and install it.
Install:
Brush Springs [A]
Negative Brush Assy [B]
Turn the stopper side [C] to inside.
Tighten:
Torque - Brush Holder S ...
Rear Frame Front Removal
Remove:
Rear Frame Rear (see Rear Frame Rear Removal)
Rear Fender Front (see Rear Fender Front Removal)
Rear Footpeg Bracket Bolts [A]
Rear Footpeg Bracket [B]
Rear Frame Front Bolts [C]
Left Rear Frame Front [D]
Remove:
Rear Footpeg Bracket Bolts [A]
Rear Footpeg Bracke ...