One of the many things that is so frustrating with the F-700 is the lousy user interface. This thing was designed behind a desk, not tested in a car. One of the problems is that the main volume knob is just too small to mess with. My solution does not look as good as what is available on the other post, but it is easy, cheap, and works great.
I went to Home Depot and bought a small bag of 3 rubber washers from the Fastener area. I think they were listed as 5/16" diameter for the center hole size and cost $ 0.79. I used clear Liquid Nails to glue the 3 together, then later to glue the