Common sander problems can easily creep up--especially on older models. Many newer models are designed with self-correcting features that plagued older versions. But, at some point, you may need to replace a part or make repairs. You may need to be a little mechanically inclined, especially if it is a motor problem but other problems may be solved with routine maintenance.
1. Motors that Run Hot
The older a power sander becomes, the more likely it will run hotter than it did in its youth. This problem will only get worse if you do not rectify the situation. Many manufacturers claim that the machine’s gear train has been permanently lubricated with heavy grease so you will need not need to worry about gear grease. However, if your machine is older than the predicted life the manufacturer sites in the original paperwork, then you might need to replace the gearbox grease. If an oily smell occurs when you are operating a sander, it is an indication that the heavier lubricating solids in the gearbox grease have separated. To remedy the problem, open the gear train box and clean out all of the old grease, replacing it with bearing grease from your local auto parts store. Coat the gear teeth so the grease fills all tooth gaps, but do not leave excess grease in the box. The newly lubricated gearbox should keep your sander working for quite a while.
2. Belt Sanders that Make Noises
Normally, when a belt sander begins making noises it is a good indication the belt needs to be changed. Worn belts will affect the tension since the belt surface area has worn with use. If you have recently installed a new belt, check the tension by squeezing the belt with your fingers. There should be about a ¼” play for a properly tightened belt. If the belt has no give, it is too tight and may cause a loud squeaky noise and overload the motor. You will need to adjust the belt tension by working the hex head set screw until you get the proper play in the belt. An excessively loose drive belt may fail altogether, slipping from the pulley, causing the sander to jump and or hesitate. Remove the drive belt cover with a Phillips screwdriver and tighten the drive pulley before replacing the cover.
3. Worn Motor Brushes
If your power sander switch is in the "on" position but nothing happens, you may have worn motor brushes. Power sanders, like all other power tools that run at high loads for extended periods of time, will tend to wear down motor brushes, especially when using models designed for casual homeowner use. The brushes will not become worn all at once. In the beginning, you will probably experience a sluggish start where you may have to shake or smack the power sander to get it to start. This is tell-tale sign the brushes are about to give it up. When brushes are completely worn, the sander will not start.