A multi-meter is a powerful tool, but resistance tests can mislead you. The Ohm scale on your electrical meter only tests the resistance in the circuit under low voltage with tiny currents. In order to get more accurate readings you must use higher current and check the voltage drop in the circuit. I show how to do this on a bad motor using a cheap power supply. The multi-meter showed a resistance of 0.1 Ohm between each commutator bar. It showed the armature is good.
But the power supply set at 7amps and 3Volts showed between most bars had a 0.8V drop, but some had 1.4V drop. Meaning some windings have higher resistance under load. This test proved that the armature is weak.
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