Written By: Jon Glinski – r.k. Miles – Middlebury, VT
Most people today own some sort of electric or battery operated tool. If you are one of these owners who use and abuse your tools, breakdowns can come unexpectedly and at the worst time. Getting your tool back up and running can be easier than you may think. Does your tool have a funny smell when it operates? Sparks when the motor starts or stops? Does it seem to have a lack of power? Have you noticed that it just does not have the performance it did when you first bought it? If so there are some simple maintenance items that may help you get out of a sticky situation and get that tool back in the field.Whether it is the carbon brushes, a switch, or a power cord — all three of these items can cause a power tool to malfunction. Your tool may not even have stopped working all together it may just be working intermittently. With a couple of simple checks you can diagnose a simple problem right in the field or tell when its time to hit the repair shop. Let’s get to it!


Every electric tool has carbon brushes. Always found in pairs, carbon brushes are what power your tool and put the electric current to the motor. Brushes are user serviceable and typically a flat head screw driver is the only tool you need to replace them. Brushes perform other functions within the tool as well. If your tool is equipped with an electronic brake it is the job of the brushes to slow the motor down with a small pulsing reverse current. Cycling a thousand times a second it can bring a spinning saw blade to a dead stop in less than a second. When brushes wear out this function can get weak or stop all together. Most people who use their tool less frequently, such as a homeowner, may never have to replace the brushes. Contractors and handymen on the other hand, who use their beloved tool all day long, five days a week, will be replacing brushes if they wish to keep the tool properly maintained. Brushes are a very cheap maintenance item and having a extra set on hand can be invaluable.

When tools are worked hard and start to generate heat or smoke STOP WORKING IMMEDIATELY. Heat builds up and can start to deform the brushes and possibly crack them. Motor damage will soon follow! Heat is what wears out brushes the fastest. The brushes can, when overheated, glaze over and cause the tool to malfunction.

A glazed and or worn out brush will have tell-tale signs…..

1. Lack of power
2. Weakening or failure of the electronic brake system
3. Sparks and or smoke *
4. Intermittent operation (start and stop)**

*When you notice a tool start to smoke, unplug it from the power source or remove the battery – this is a good time to go grab a bite to eat and let the tool cool down. It may be possible to continue work after the tool has cooled off but I would recommend checking it over first.

** intermittent operation can also be a switch or cord. I will be covering these topics in the following two installments of this series.

Now that we know the tool has a problem let’s take a look at the brushes and some typical brush locations. I could write all day long on the types of brushes and their holders, but a picture says a thousand words so here are some for you. Basic tools such as a screwdriver and pair of needle nose pliers are all you need. And remember ALWAYS REMOVE the BATTERY or UNPLUG the POWER TOOL BEFORE SERVICING BRUSHES

Your tool may differ from the ones pictured here. Consult your owner’s manual and it will tell you the type of brush and its location. If you are unsure of where your brushes are and how to replace them bring your tool to r. k. Miles and we can help you. (I think this is the whole point of the exercise!!) With proper maintenance your tool can last a lifetime. Please be careful when trying to perform any service on power tools.)

Remember, trained professionals are the ultimate caretakers of your equipment and this guide is to be used to get you out of a jam and just give you a little information as to how your tools work.


Jon Glinski works at rk MILES’ Middlebury store. Look for Part 2 of his Tool Repair Blog to come!

Questions for Jon, call or email him: 802-385-1134 direct glinskij@rkmiles.com



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