At the same time, press on the brush to increase pressure.
Brush Seater, 4-3/4 in X 1-1/4 in X 3/4 in, Grade Fh Our Brush Seaters come in 5 grades: ES EX tra Soft, FH Fine Hard, MS Medium Soft-our most popular, FS Fine Soft, and MH Medium HardBrush Seaters are used to easily and accurately seat commutator and slip ring brushes of any material. For best results, use a stone with a width equal to or greater than the width of the brush.