I have one of those shower dials with one dial to control hot and cold. I can do some small repairs but Iam just too apprehensive to do this one. The problem is that its dripping. Any other fixture I know all I have to do is replace the washer, but I dont even know where to start with this. If it matters, there is no name on the cover plate to tell me who makes this particular one. Can anyone help me here? Thanks