While brushed motors are not as efficient as the newer brushless motors, they are simple, cost-effective to manufacture and make up the staple of the value range of the power tool industry.

The brushes, where the brushed motor gets its name from, conducts electricity from the battery to the commutator. The commutator acts like an electric switch, changing the eletromagnet polarity which acts against the external fixed magnets to push or pull which in turn creates a rotational motion. Typically, the brushes in a brushed motor are typically made of carbon as carbon is conductive, fairly soft and will wear before the metallic fingers on the commutator.

As the carbon brushes are pushed against the commutator with a spring, the more you use your tool or the faster your tool spins, the faster the carbon brushes wears out.

Fortunately, most manufacturers have made provisions for ease of brush replacement with easy-to-access caps located on the sides of a power tool. While some tools have quick-access ports, others require that you completely remove the tool housing to access the brushes. Either way, the method are the same - remove the worn out brushes and replace with a fresh pair.

A new pair of replacement brushes typically sells for around RM10 per pair but depending on tool models, they can sometimes go up to RM50 per pair.

In this example, we'll be using the Bosch GSB 180-LI Professional. To perform this service, you'll need a coin, a small pick or a pair of needle-nose pliers and new brushes. Coincidentally, the recently-issued Malaysian 10 Sen coin fits perfectly in the GSB 180-LI. Do not use a flat-head screwdriver as the smaller size of the flat-head will leave marks on the plastic end-caps.

With the cap off, you should see the back of the brush. The worn brushes should slide out without much resistance but if they are somewhat reluctant to come out, gently pry or pull on the tabs of the worn brush with a small pick or a pair of needle-nose pliers.

With the brushes out, you may optionally choose to lightly blow out the remaining carbon dust with an air gun before reinstalling a new carbon brush, they'll only go in one-way, replace the cap and you're done!

Tip: You can continue to use your brushed power tool until the brushes wears out - when the brushes no longer contact the commutator, it would naturally stop. Just make sure you have your replacement brushes handy! You could also regularly inspect the brushes or blow out the carbon dust. But it's often not necessary.