Brushes need replacement when the carbon is mostly worn away or if the carbon is badly pitted or broken. **All Electrical parts are non-returnable if installed**??? DeWalt Miter Saw replacement Carbon Brush & Spring (Sold Individually) - 145323-06??? DeWalt and Black & Decker Electric Drill replacement Brush - 158459-00 (Sold Individually)??? DeWalt Drywall Screwdriver replacement Carbon Brush - 1