If its leaking when faucet is in off position than seats and springs will need to be replaced. To do this shut off water to faucet both hot and cold. The handle is held on by a allen head set screw on the back side of handle . Loosen set screw and carefully remove handle,this make take alittle persuasion but don't force it. Carefully rock back and forth and tap lightly on base of handle .When you get handle off the round cap assembly will need to be removed,it has serrations at bottom to grip it withchannel lock pliers. You need to be very careful here and not use too much force because if you do you will twist copper fittings inside of faucet and ruin it. If it does not come loose fairly easily by turning counterclockwise you can use a mini hack saw or just hacksaw blade and carefully split cap on back side. Go slow stopping often to make sure you don't go any deeper then absouletly neccesary. If you slightly mark retaining threads it's not terrible. Most of the cut is not to bad because all parts immediatly underneath are easily replaced. When you get almost all the way thru take a large blade screwdriver insert in slot you have cut and twist back and forth to break cap the least of the way. Cap will be easy to remove now,take it off and pull out control ball along withrubber seal. There will be a small round rubber seat on bottom,one for hot and one for cold remove them and springs underneath them.Replace all parts that may have been damaged.needless to say you will need cap and seat and springs at the least.Repair kits are redily available just follow instruction and you should be fine.I know it's a pain but if you take your time you can save a good faucet. Hope this helps. Thanks