I've had a Kohler master shower for about 10 years or so, and the volume control trim knobs have come off. This is a link to a picture of the knob, http://www.plumbersurplus.com/Prod/Kohler-K-T9472-7-CP-MasterShower-Volume-Control-Trim-with-Cylinder-Handle-Polished-Chrome/45182/Cat/1196...