Parts Replacement & Testing: Armature

Test for shorts between windings on a growler. Check armature for grounding using a test lamp. Check for open circuit on growler. Maximum commutator out-of-round must not exceed 0.015" and commutator mica must be undercut at least 0.012" throughout its entire length and width. Turn commutator with suitable lathe if necessary, and clean with a dry rag. Ensure that mica segments are clear of chips or foreign material.