1. Slow down the ring gear of the stand, turn on the starter and measure the current, voltage and braking torque, which for the starter 35.3708 should be respectively no more than 550 A, no more than 7.5 V and no less than 13.7 Nm (1.4 kgf·m). For the ST-221 starter, the current should be no more than 500 A, and the voltage should be no more than 6.5 V. The duration of the starter on should be no more than 5 s.
2. If the braking torque is lower and the current strength is higher than the specified values, then the interturn short circuit in the stator and armature windings or the short circuit of the windings to ground may be the reason for this.
3. If the braking torque and current consumption are below the above values, then the cause may be oxidation and contamination of the collector, severe wear of the brushes or a decrease in the elasticity of their springs, brushes hanging in the brush holders, loosening of the stator winding leads, oxidation or burning of the contact bolts of the traction relay.
4. When the gear is fully braked, the starter armature should not rotate; if it does, the freewheel is faulty.
5. To troubleshoot, disassemble the starter and replace or repair damaged parts.