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 InspectionAir Suction Valve Inspection
Remove the air suction valve (see Air Suction Valve Removal).
Visually inspect the reeds [A] for cracks, folds, warps,
heat damage or other damage.
If there is any doubt as to the condition of the reeds, replace
the air suction valve as an assembly.
Check the reed contact areas [B] of ...
Balancer Installation
Position the crankshaft at #2, 3 positions TDC or at #1, 4
positions TDC.
Install the balancer assembly as follows.
Align the punch mark [A] on the weight and the projection
[B] on the crankcase.
Engage the balancer gear and the crankshaft gear.
Insert the balancer shaft until it is bot ...
Stick Coil Installation
Apply a thin coat of grease [A] to the stick coils for easy
installation.
Insert the stick coils so that the coil heads align with the
lines [B] on the cylinder head cover.
NOTICE
Do not tap the coil head while installing the coil.
After installation, be sure the stick coils are ...