How do I clean dirty battery contacts on a battery-powered chainsaw?

Use a cotton swab dipped in 91% isopropyl alcohol to wipe the metal tabs on both the battery and the saw. For stubborn sap or corrosion, use a stiff nylon brush like an old toothbrush. Let everything dry fully before reassembling. Don’t use sandpaper or metal files—scratched contacts just collect more gunk.