If you can’t loosen the Allen screw on the handle of a ball-type faucet, don’t let that 15¢ screw force you into a $100 faucet replacement… just yet! Normally you have to remove the handle to get the worn rubber seats that cause the drip (Figure A). First try spraying the screw with penetrating oil every day for a week. Then try the screw to see if it’ll come (Photo). If this doesn’t do it, or if you finally strip the head of the Allen screw, try drilling out the screw. Use a bit about the same size as the screw and work carefully. You’ll ruin the handle and have to replace it, but it’s well worth it if you can save the valve. As a final resort, you can actually unscrew the cap with the handle still connected (see Figure A for the parts). This is tricky, because you can’t grab the flat edge of the cap, the part that’s shaped for the pliers (Figure A). Make sure to cushion the jaws well when you grip the smooth, rounded body of the cap. Use rubber tape, because you can’t squeeze the cap too hard. Turn the cap counterclockwise to unscrew it. The assembly you remove will contain the handle, cap, cam, packing and ball (Figure A).
The next challenge is to break the ball from its stem. (The Allen screw clamps onto the stem.) Try grabbing it with the pliers and twisting. The goal is to separate the parts so that you can salvage and reuse the cap. You’ll still have to buy a new handle and a repair kit that includes a new ball.
If this doesn’t work, the only solution is to replace the entire faucet. This is a tough fix. Good luck!