Bench Testing: Commutator

Inspect commutator for roughness, grooves, burns, pitting and out-of-round. If necessary, sand lightly with 500-600 grit sandpaper. If mica insulator undercut is less than .008 in. (.20 mm), undercut to .020-.031 in. (.50-.80 mm). Replace armature if commutator diameter is less than specified. See STARTER SPECIFICATIONS .