As far as faucets go, Price Pfister is a well-known name, but the company has changed it and is now known simply as Pfister. When your Pfister faucet leaks, you can almost always trace the problem to the cartridge, which is the internal water valve under or behind the handle. Some older Pfister faucets have ball valves, and while they fail for a different reason than cartridges, the repair isn't any more complicated.
Determine the Problem
If your faucet drips from the spout -- and you can't seem to stop it -- it's a sign that the valve seals have worn. Water dripping from the handle is a different -- and less common -- issue that usually means the valve wasn't installed properly. If the lever or handle gets stuck, it means your water is full of minerals, and these have formed deposits on the valve mechanism. In all cases, the repair procedure involves removing the valve.
Check the Aerator
Before you disassemble the faucet to service the valve, unscrew the aerator from the faucet spout and examine the screen. You may find that it's full of mineral deposits, and if so, that's the reason you don't have any water pressure. Soak the aerator overnight in vinegar to dissolve the deposits.
Parts and Tools
You don't need many tools to disassemble a Pfister faucet, but you do need a specific one that you may not already have -- a 3/32-inch hex wrench -- also known as a Allen key. This size isn't included in most standard Allen key sets. You may have to order replacement parts, and to do this, you'll need the model number of the faucet. To do this, you may have to compare the faucet with models on the FAQ page on Pfister's website. Some gaskets, washers and valves are standard ones that you can find in a hardware or plumbing supply store. Many Pfister faucets take the WKP-5 cartridge, so you should be able to find one of these at any hardware store.
Disassembly and Repair Procedure
Before disassembling your faucet, you need to turn off the water. If it's a sink faucet, you can turn off the shut-off valves under the sink, but if it's a shower faucet, you may have to turn off the water to the house and keep it off while you make the repair.
Look for a decorative button somewhere on the handle and pry it off, using a flat-head screwdriver. If you don't see a button, look behind the handle or under the lever for recessed set screw. Unscrew the screw with a 3/32-inch hex wrench and lift off the handle. Some new Pfister faucets have Phillips screws that you can remove with a Phillips screwdriver.
The majority of Pfister faucets have cartridge valves. To release one of these, unscrew and remove the metal bonnet -- which you can do by hand -- and unscrew the retaining nut with adjustable pliers. You should be able to pull out the cartridge.
If the faucet has a ball valve, unscrew the metal bonnet to expose the ball, then lift it out.
You don't have to worry about seals when repairing a cartridge valve -- just lift out the old valve and insert a replacement, making sure that the cartridge is aligned in the same way as the one you took out.
Ball valve seals, on the other hand, frequently wear out. You'll see small gaskets and springs in the holes in the bottom of the valve seat. Pry these out with a screwdriver and insert identical replacements. If the ball is nicked or gouged, replace it.
Reassembly is usually the reverse of disassembly, If you have any trouble screwing something back together, don't force it. Separate the components you're joining and realign them. Forcing misaligned threads usually leads to leaks and the need for extra parts.