Armature Test

Ensure armature is not grounded. Place armature in growler. Hold a thin steel blade parallel to, and just above the armature while slowly rotating armature in growler. A shorted armature will cause blade to vibrate and be attracted to core. Using an ohmmeter, check continuity between armature coil cores and commutator segments (small diameter end of armature). Continuity should not exist. Check for continuity between segments. Continuity should exist. Replace armature as necessary.