My faucet does not leak when the (blue) knob is turned off. However, when I put a cap on the spigot or connect a hose to it with the nozzle shut off, then turn the faucet on, water leaks around knob! When I remove the knob, there is a round plastic part protruding from the end of the pipe; before I remove it with pliars and possible ruin it, I wanted your opinion.

I can send a digital photo if that would help! Thanks, Bill