The price pfister shower valve not only leaking but also lets through only hot water barely turned on. There is a diverter knob on the tub spout that does not close well due to hard water deposits. I would like to replace the diverter/tub spout but does the entire mixing valve need to be replaced as well? If so the entire tiled shower wall have to be accessed costing several thousand dollars! Is there any way this repair can be done without demolition of the wall? Please advise ASAP. Waldo