I have a 70's type shower/tub setup with price pfister faucet. It's the type that has 3 knobs- 1 hot, 1 cold and 1 for either tub or shower. The hot faucet was leaking when shut off, so I replaced the stem assembly in both hot and hold and also replaced the seats. Now the cold is either full on or totally off it seems, when off I can turn it 1/4-1/2 turn and nothing happens then all of a sudden it's fully on. However this wasn't the case for the first week or so after the rebuild. What did I do wrong?