The mono-bloc mixer tap in my kitchen had been dripping since I moved in. I removed the swivel spout (with both hot and cold turned off) and noticed that water was still slowly welling up from the base of the tap. Called plumber, was advised that the base could not be dismanteld and that a new tap would be needed. Purchased new mixer tap, plumber came and fitted it. But it still drips! Admittedly slower than before, but it definitely still drips. What could the problem be? Could someone help?