In a home I recently purchased, several knobs are missing from a bank of Lutron dimmer switches (GL-600 ?) that I assume were installed decades ago. I have purchased both Skylark and Glyder (GK-IV) replacement dimmer knobs, none of which fit. I will post images here, if I can figure out how to do that.... Can anyone identify the knob that I need, and suggest where I might find them? Again, the Glyder replacement knobs I bought do not fit (they fall right off).