Collector cleaners are used to improve the contact between carbon brush and collector. Over time, carbon deposits form on the collector or the carbon brush holder. This process reinforces itself, causing dirt to build up faster and faster and eventually the carbon brush gets stuck. With the annual maintenance you can prevent problems by cleaning the collector and carbon brush housings. With the standard cleaners you can polish everything nicely. With the stone cleaners you can repair stubborn deposits or an uneven worn collector.