If your Delta or Peerless brand single-handle faucet is dripping, a little time and a Delta/Peerless faucet repair kit will solve your problem lickety-split.
Step 1: Turn the water supply off to the faucet using the shut-off valves below the sink. Turn on the faucet to drain any water left behind.
Step 2: Use an Allen wrench to loosen the set screw on the underside of the faucet handle. Lift the handle up and off the faucet.
Step 3: Use a locking wrench to remove the dome shaped cap assembly beneath the faucet handle. Wrap the wrench jaws with duct tape to prevent scratching.
Step 4: Pull up on the ball stem to remove the cam assembly and ball.
Step 5: Remove the spout by pulling it up and off the faucet.
Step 6: Replace the two o-rings found beneath the spout with new o-rings from the kit.
Step 7: Use a towel to soak up any excess water in the faucet body. You will see two black circles inside the body. These are rubber seats. Use a flat screwdriver or dental pick to remove the seats and springs below them.
Step 8: Replace the seats and springs with new ones from the repair kit. If you have trouble getting them in place, slide a rubber seat onto the screwdriver shaft, followed by a spring. Place the screwdriver into the empty hole and let the spring and seat slide down the shaft. Slip the screwdriver out and carefully press the seat and spring into the hole. Make sure both seats are level before proceeding.
Step 9: Examine the old ball and cam assembly for any wear spots or cracks. If either is worn in the slightest bit, replace it with the new part from the kit.
Step 10: Place the ball back into the faucet, sliding the slot in the side of the ball over the pin inside the faucet body.
Step 11: Replace the spout, followed by the cam assembly and the cap assembly.
Step 12: Test to be sure the ball moves freely in the faucet body. If it seems too loose or too tight, move the plastic ring at the top of the cap by pushing a flat screwdriver against one of its notches. Turn the ring clockwise to restrict the ball movement and turn it counter clockwise to loosen it.
Step 13: Replace the handle, tighten its set screw and turn the water back on.