While Delta single-handle ball faucets are generally reliable, they can spring leaks. Years of wear and tear can result in annoying and wasteful drips from the base of handle or from the aerator. The good news is that repair kits are readily available. However, if you can't locate a Delta-brand repair kit, a universal sample should suffice as long as the package states that it will work with a Delta faucet.
Adjust Ring at Base of Handle
Close the shutoff valves under the sink. Alternatively, if there aren't shutoff valves under the sink, turn off the water at the water meter, usually in the basement or a crawl space. Turn the faucet to both hot and cold to allow each to drain completely.
Remove the plastic plug from the handle of the Delta kitchen faucet by prying it off, using a slotted screwdriver. Be careful not to scratch the finish.
Unscrew the hex nut under the plastic cap, using an Allen wrench. Pull the handle off of the faucet and set it aside. Put the nut in a place where it won't get lost.
Tighten the ring with a spanner wrench, which should come with the repair kit. If it doesn't, purchase one from a hardware store or home center. Reattach the faucet handle, using the hex nut and Allen wrench. Turn on the water and test the faucet.
Replacing Seals and Springs
Turn off the water at the shutoff valves or water meter. Turn the handle to hot and then cold to drain all the water from each side.
Pop off the plastic plug on the handle of the Delta faucet. Unscrew the hex nut underneath the plug, using an Allen wrench. Set the handle and hex nut aside in a safe place.
Grip the cap at the top of the faucet and turn it counterclockwise. Alternatively, use adjustable pliers if the cap won't move. Wrap a plastic glove around the collar to prevent marring of the surface when using adjustable pliers.
Remove the cap and adjusting ring, cam, packing, stainless steel ball, seats and springs. Pay close attention to the order in which the parts are removed.
Install the new parts that came with your repair kit in the same order you removed the old parts.
Reattach the cap and adjusting wring. Do not to overtighten it.
Reattach the handle of the Delta kitchen faucet, using the hex nut and Allen wrench. Turn on the water and test the faucet.