I have a Price Pfister Marielle three piece kitchen faucet assembly (26-3NXX) and there is a leak at the spout (both at base and top)I have not yet disassembled the spout (I have the schematic) but aside from washers what else cold be leaking. On the schematic I see a part (971-002) just below the cap on the spot but nowhere does it ell me what this is or what it does. Suggestions please.