Check both motor brushes after every 50-60 hours of use by unplugging the tool, opening the brush caps and removing the carbon piece from the holder; if there is less than 1/8" of carbon left on either brush, they both should be replaced
For use with Dremel Rotary Tool Models: 100, 200, 275, 285, 300, 395 and 595 (Types 4, 5 & 6) as well as Dremel Contour Sander 6000 (Types 1 & 2)