... use life,safety HITCACHI carbon brush,HITACHI 99-012,carbon brush for power tools,power tools carbon brush,carbon brush replacement Size6.3X8X16/18Code ... the brush to slide freely. Brush holder fingers must move freely and if the unit consists of constant pressure ... to be "off neutral".Brush Holder Spring Tension: Maintaining the proper spring pressure reduces arcing, brush wear, heating, and commutator ...