When a plastic spring breaks on a molded plastic tongue, it is possible to replace it (very useful if the style of tongue is unavailable). Cut a narrow slot in the tongue in line with the missing spring. Drill a hole at the end of the hole. Take a piece of thin (.008" or so) spring wire and make a 90 degree bend at the end. Insert the bend into the hole, lay the rest of the wire in the slot. Melt the slot closed with a soldering iron. Cut the spring to length and make a bend at the end so it doesn't catch in the slot (the rough end of the wire).