Do not attempt to remove the inside unitPull flint wheel cartridge straight upTurn cartridge upside down and remove screw with thin coin or small screwdriverRemove any remaining old flintInsert a new flint in the tubeFor best results, use only Zippo brand flintsReplace the screw in the flint wheel cartridgeTighten screw securely in placeReplace flint wheel cartridge in lighter, lining up notched side of cartridge facing the burner and press firmly downClick here to view video clip.