Component Testing: Commutator

If out-of-round is more than .002" (.05 mm), turn the commutator on a lathe until out-of-round is within specification.
Wear or cutting limit of commutator is 1.08" (27.5 mm) on Mitsuba starters or 1.14" (29.0 mm) for all others.
If worn less than .008" (.20 mm), insulating mica should be undercut to a depth of approximately .015-.031" (.40-.80 mm).