110RD-50 Amp Knob Needed

I need a knob for my 1980s Music Man 110RD50. Any one have one for sale?* Thanks.
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* Plastic needs to be good. Prefer one with the aluminum insert and tightening screw, but will consider ones lacking those parts. I assume most people on this Forum are familiar with the knobs, but just in case I have attached a photo.