have a kitchen tap which has a centre spout with left tap for hot and right tap for cold. The cold tap is jamming in that when it is turned on the whole cold tap starts to unscrew and therefore to leak. I managed to take the casing off to show the tap itself and holding the nut with a shifter the tap turns on with a bit of force. Unfortunately it soon becomes jammed again and is not a solution. I'm no expert but it feels as if something is sticking somewhere. I can get the tap off completely but the water needs turning off at main. Our system does not include a water storage tank or hot water tank. Would the whole system need to be drained before the tap is removed or would turning off at main be enough? 
