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 Intake Solenoid Valve Unit Test
Remove the air intake solenoid valve (see Air Intake Solenoid
Valve Removal in the Fuel System (DFI) chapter).
Set the hand tester [A] to the × 1 Ω range and connect it
to the air intake solenoid valve terminals as shown in the
figure.
Special Tool - Hand Tester: 57001-1394
...
Radiator Hose and Pipe Inspection (coolant leak, damage, installation
condition)
The high pressure inside the radiator hose can cause
coolant to leak [A] or the hose to burst if the line is not
properly maintained.
Visually inspect the hoses for signs of deterioration.
Squeeze the hoses. A hose should not be hard and
brittle, nor should it be soft or swollen.
Repl ...
Throttle Control System Inspection
Check the throttle grip free play [A].
If the free play is incorrect, adjust the throttle cables.
Throttle Grip Free Play
Standard: 2 3 mm (0.08
0.12 in.)
Check that the throttle grip [B] moves smoothly from full
open to close, and the throttle closes quickly and completely
by the ...