Recently fitted monobloc mixer to ceramic sink.However I daren`t risk overtightening fixing nut for fear of cracking sink,consequently,if the spout is moved,the whole unit moves!Supplied with the tap were one steel "e" washer,one rubber washer and one rubber "e" washer,there was also an optional tap body base ring,which I left on.Would you say there are fittings missing,if so ,can I get them?Any advice appreciated!