The motor brushes in your Dremel tool will wear down with normal use so they should be checked every 50 hours or so. To check them unplug the tool and unscrew (lefty loosey) the brush caps with a small flat head screwdriver. The carbon brushes are held in with springs which should come out easily or with careful prying with the screwdriver if needed. If either of the carbon brushes are less than 3.5mm long they should both be replaced.
FOR DREMEL MODELS
If your Dremel model is not listed above check with us we can get them for other models.
2 x Carbon motor brushes
2 x Contact springs