What problems will occur if the carbon brush is broken?

[PiperAnn]

The starter motor will not rotate or will lack sufficient power if the carbon brush is broken. Symptoms include hearing a slow and weak starting sound or only the sound of the small flywheel operating mechanism working. The engine may not start or even fail to start. Note: The starter is only used during startup. Generally, the carbon brushes in a vehicle's starter can last over ten years without issues. However, frequent starting difficulties caused by other reasons, requiring multiple ignition attempts, can accelerate carbon brush wear and shorten their lifespan. Carbon brushes are primarily made of graphite containing copper and silver, used to transfer electrical energy between the stationary and rotating parts of the motor. The carbon brush in the starter is block-shaped and is pressed against the starter's commutator shaft by spring preload. To move the engine's flywheel crankshaft and connecting rod mechanism, the starter requires significant torque, which is why it includes a planetary gear mechanism to reduce speed and increase torque.