battery operated bicycles sound reasons for abnormal motor faults and solutions

Reason 1: The battery powered bicycles motor body deflection,
Approach: re-adjust the body.
Reason 2: Electric steering surface oxidation, erosion, oil uneven, loose commutator,
Approach: Cleaning battery power bicycle commutator surface or weld commutator.
Reason 3: Brush loose brush holder is not correct,
Treatment: adjustments.