CARBON BRUSH ASSEMBLY|Carbon motor brushes are one of the most commonly replaced power tool parts. The reason is that carbon brushes are wear items, meaning that through friction and use they will gradually wear away and eventually will need replacing. Worn brushes are a common causes of intermittent motor function, reduced electric braking and reduced motor power. A worn-out brush will often be worn down near to the wire lead and can be cracked, pitted, or burned. When replacing carbon brushes, also check your armature for burns, cracks, or other damage which are indications of a larger motor problem needing attention.