The O-rings will need to be replaced. The http://www.moen.com web site has nice pictures of faucet breakdowns. You will need the free download able Adobe software to view the PDF files, but well worth it. The process is mainly removing the top nuts, removing the spout, replacing o-rings, and reassembling. Other thins to consider, turning off the water, applying plumbers grease to the o-rings. My personal preference on faucets over twenty years old, is to replace. Like anything that has constant wear and tear, things to wear over time and lose tolerances. Terry