Advice please! I am part way through changing the taps on my cast iron bath and have discovered the holes are square. The new taps have a round rubber washer for the underside that does not match the square holes. I want to be sure the taps are held firm and do not start to rotate in their hole when turned off. The old ones seemed to be cemented in with what looked like putty, should I do the same ? Take care, God Bless. Ken