4-24. ELECTRICAL SYSTEM - Continued
Separate lever housing and field frame. Pull armature out of lever housing.
Separate solenoid from lever housing by pulling apart.
Clean armature, field coils and other components with a clean, lint-free cloth and/or a soft bristle brush.
Clean commutator with No. 00 sandpaper (item 24, Appendix E).
Inspect brushes and springs. Replace if worn, broken or chipped. Be sure springs have some springiness
and show no signs of overheating. Replace whole brush assembly rather than individual components.
Be sure brushes do not bind to the brush holders. Clean as required.
Inspect armature commutator. If it is worn, out of round by more than 0.003 in. (0.08 mm), or insulation
between strips is high, place armature in a lathe. Turn down the commutator until there are no more high
or worn spots.
Undercut the insulation so that it is 1/32 in. (0.8 mm) wide and the same dimension below the surface of
the commutator. Lightly sand complete unit, and with a soft brush and cloth, remove all traces of dirt and
copper filings from commutator slots.
Check electrical continuity of the armature.
Open circuits most likely occur at the commutator to winding connection. Poor contact causes burning and
arcing on the commutator bars. If the burning is not excessive, repair can be effected by resoldering the leads
to the riser bars using a rosin flux. Replace armature if open circuit cannot be repaired.