I know I have been in the bottom of the pool holding my breath, going to town on some pop up heads that wouldn't budge. Nothing is more frustrating than breaking your pop up tool and not having a backup. Well, there is now a fix. All of the manufactures make a metal version of the tool that are reinforced. These things are very strong. I have personally taken a pair of Channel Lock pliers to a metal Caretaker tool to remove a head. I did not break the tool!
Under the sections for the pop up heads are the tools needed to get the stubborn heads out.