I have a weird problem with a kitchen faucet. It's a "Central Faucet" wall mounted faucet with separate valves for hot and cold. On the hot side I get a bit of free travel from off before water comes out and then there's a spot where if you stop there sometimes there's a loud vibration -- as long as you go past that point it's fine. Sometimes in use it seems to "reset" itself to the vibration "setting". This never happens if the valve is totally open. The cold side works fine and none of the other faucets in the house have this issue. Is there a cartridge in the faucet that I need to replace? Is this a "water hammer" that needs some other fix? I'm only familiar with single handle faucets so I'm at sea with this. Thanks!