Well.. it's ugly as sin, but it atleast works, and doesn't cost much.

Radio Shack Part Number 274-415A
3/4" Hexagonal Control Knobs
1/4" shaft

slip it on.. tighten it down gently, and it works fine.. just make sure you keep it off enough so you can press the button..

empeg guys: why make the knob all plastic.. why not use a setscrew metal sleve and mold your knobs to it... maybe the guys that sell the knobs make a setscrew thing.

12gig green mk2 -- 080000125