Low servo motor torque, vibration or overcurrent may be related to the windings, encoder, bearings or drive. The power and feedback circuits should be checked separately during diagnosis.
Measure the resistance and insulation resistance of the three-phase windings, check the encoder waveforms and connector condition, and assess bearing rotational resistance.
After repairs, test current, speed and positioning accuracy, and ensure that the temperature rise during continuous operation remains within the normal range.