Carbon brushes in a washing machine motor are wear parts that transfer electrical current to the rotating armature in brushed (commutator) motors. They maintain contact with the commutator surface, allowing the motor to start, change speed, and run under load.

Over time the brushes shorten from friction and must be replaced. When they are worn out, the motor may lose power, run intermittently, produce sparking or a burning smell, make unusual noise, or the machine may stop and show an error code. Timely replacement helps restore stable operation and prevents damage to the commutator.