• Inspect the commutator (1) for insulator (2) depth.
Correct or replace if below limit.
Commutator insulator depth "a"
Standard: 0.4 – 0.6 mm (0.016 – 0.023 in.)
Limit: 0.2 mm (0.008 in.)
• Check the commutator and armature core. If there is
continuity, the armature is grounded and must be
• Check for continuity between segments. If there is no
continuity at any test point, there is an open circuit
and the armature must be replaced.
Inspect the internal gear and the planetary gears for
wear, damage or other abnormal conditions. Replace if
Pinion and Over-Running Clutch
• Inspect the pinion for wear, damage or other abnormal
Check that clutch locks up when turned in direction of
drive and rotates smoothly in reverse direction.
Replace if necessary.
• Inspect the spline teeth for wear or damage. Replace
Inspect the pinion for smooth movement.