I had just installed a new branch of 1/2" galvanized threaded pipe to an outdoor garden hose faucet. All the threaded connections were wrapped w/ teflon tape and none of them leak except for the joint between a new 90-degree elbow and a new gate valve. The leak is very slow...about a drip a minute...and i've tried tighening the joint further, but it's still dripping at the same rate. is there any repairs that doesn't require me to undo all the connections and redo the one leaking joint?? Thanks.