What are the symptoms of a bad starter carbon brush?

[DiNora]

Starters with bad carbon brushes may exhibit the following symptoms: the motor either fails to turn or lacks sufficient power, manifesting as slow and weak cranking sounds or only the clicking noise of the pinion gear operating mechanism. The engine may struggle to start or fail to start altogether. The starter functions similarly to the hand crank used in old tractors. During engine startup, the starter's operating mechanism pushes the pinion gear outward to engage with the ring gear on the flywheel. Once engaged, the starter rotates the flywheel, initiating movement in the engine's piston-connecting rod assembly to start the engine. In reality, the starter is only used during the starting process. Typically, the carbon brushes in a vehicle's starter can last over ten years without issues. However, frequent starting attempts due to other causes of starting difficulties can accelerate carbon brush wear, shortening their lifespan.