I have a one handle bath tub water spout. The first part which is round turns the water on. Behind that is a handle that turns from cold to hot. That handle is turning hard. I have taken them off and there is a (looks like hex nut) on a pipe which goes into the wall. I do not know if that is all one piece or not. How do I losen it so that the hot/cold will turn more easily. It just keeps breaking the handles.