Frank,
Thanks for the info. The new knobs I am wanting to use have 2 6-32 set screws on each knob. They also have 1/4" shaft holes. They also vary in outside diameter from .500 inches up to .925 inches. My other question was if anyone knew what the outside diameters are of the current larger selector, volume and balance knobs and the smaller tone control knobs. Also are the knobs recessed into the front panel, of are they flush with the panel? The model I am asking about is the Insight+ EC preamplifier.