TM 5-4240-501-14&PSTARTERSNicad System2.Starter motor brushes sticking in brushholders.3.A dirty or worn armature commutator.4.A shorted, open or grounded armature.A.Shorted armature (worn insulation, wirestouching each other) will be indicated by slowspeed and high current.B.Open armature (broken wire) may not turn orwill have low RPM.C.Grounded armature (worn insulation, wiretouching armature) will not turn or may turnslowly and will have excessive current(amperes).5.Weak magnets.DISASSEMBLY OF STARTER MOTORStudy Fig. 50 prior to Starter Motor Disassembly.Remove the starter cover, nylon spur gear retainer andthe nylon spur gear. The three screws holding the gearcover and the gear itself may now be removed. Lift theclutch assembly and the pinion gear off their respectiveshafts.Remove the starter motor thru bolts. Separate motorend head from motor housing. Fig. 56. Push motorarmature out through bottom of starter housing, takingcare to slide rubber mounted terminal out of motorhousing along with end cap. Fig. 57.Fig. 56 - Removing Thru BoltsFig. 57 - Removing ArmatureBefore removing armature from end cap, check brushesfor freedom of movement. If brushes are found to besticking in their retainers, this must be corrected, or poorstarter motor performance will result. Fig. 58. Ifbrushes are worn to a length of 1/4" (6.4 mm) or less, thebrushes should be replaced. Check brush springs forproper tension (sufficient force to keep brush in firmcontact with commutator).Fig. 58 - Checking BrushesClean all dirt accumulations from armature, end cap,motor support, gears, etc. The end cap bearings andarmature should not be soaked in a solvent. Thearmature commutator may be cleaned with a finesandpaper or commutator paper. Do not use aluminumoxide paper or emery cloth, as emery will embed in thecommutator and cause rapid brush wear.If the armature is suspected to be defective, a newarmature should be tried in the motor. If proper testingequipment is available, check the suspected armature todetermine if it is defective.14
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