Commutator Test

Using "V" blocks and dial indicator, check commutator runout (out-of-round). See STARTER SPECIFICATIONS . Turn commutator/armature on lathe until runout (out-of-round) is within specification.
Check commutator diameter. If commutator is less than specification, replace armature. See STARTER SPECIFICATIONS .
Ensure continuity exists between any 2 commutator segments. If continuity does not exist, replace armature.
Clean commutator segment surfaces with emery cloth and polish with No. 400 grit sandpaper (if necessary). If surface is scored, out-of-round, or pitted, turn commutator/armature assembly on a lathe.
Measure undercut depth of insulating mica. Refer to the STARTER SPECIFICATIONS . If mica depth is not within specification, undercut to specified depth using hacksaw or replace armature.