'Smartie' type control knob

[Cathode Follower]

Hello all,

I'm trying to get hold of one of those so called 'smartie' (as in the tasty chocolate treat!) control knobs for a Sound City head. You know the ones - black body with a coloured top and a numbered clear-plastic surround. They had them on a few of the late 70's Orange PA models if I remember rightly. I'm looking for one with a green top. If anyone could help me out or point me towards someone who can I'd be very much obliged!

Many thanks,

Richard