To change the tip on a Weller wood burning tool, you will need to ensure that the tool is unplugged and has had enough time to cool down. Once it is safe to handle, gently grip the metal collar located behind the heat-resistant handle and rotate it counterclockwise. This will loosen and unlock the tip holder. Carefully remove the current tip by pulling it straight out from the holder. Take your desired replacement tip and insert it into the holder, making sure it is fully seated and secure. Finally, turn the metal collar clockwise until it tightens snugly against the new tip, locking it in place. Always remember to exercise caution when handling hot tools.