Armature Test

Disassemble the starter. See Figure.
Inspect the armature for wear or damage from contact with the permanent magnet. If there is wear or damage, replace the armature. See Fig 1.
Check the commutator (A) surface. If the surface is dirty or burnt, resurface with emery cloth or a lathe within the following specifications, or recondition with # 500 or # 600 sandpaper (B). See Fig 2.
Check the commutator diameter. See STARTER SPECIFICATIONS . If the diameter is below the service limit, replace the armature. See Fig 3.
Measure the commutator (A) runout. See Fig 4. If the commutator runout is within the service limit, check the commutator for carbon dust or brass chips between the segments. If the commutator runout is not within the service limit, replace the armature. See STARTER SPECIFICATIONS .
Check the mica depth (A). If the mica is too high (B), undercut the mica with a hacksaw blade to the proper depth. Cut away all the mica (C) between the commutator segments. The undercut should not be too shallow, too narrow, or V-shaped (D). See Fig 5.
Check for continuity between the segments of the commutator. If an open circuit exists between any segments, replace the armature. See Fig 6.
Place the armature (A) on an armature tester (B). Hold a hacksaw blade (C) on the armature core. If the blade is attracted to the core or vibrates while the core is turned, the armature is shorted. Replace the armature. See Fig 7.
Check with an ohmmeter that no continuity exists between the commutator (A) and armature coil core (B), and between the commutator and armature shaft (C). If continuity exists, replace the armature. See Fig 8.