[gary rabbitt]

Hi Robert,
I assume you have tried Mike Koste or David Frush on the Resources page?

If you're looking for a gear, you might want to try an R/C helicopter/ car site. Some have used R/C gears to substitute for their dial drives, etc. especially ones that were made of crumbling pot metal.
2 examples:
http://www3.towerhobbies.com/cgi-bin/wti0093p?&C=EEE

http://www.robinsonracing.com/index.html

Of course a custom molded knob by Larry or someone would be best, but until then you might have to rig something up.

I don't know what the knob/gear looks like , so I can't recommend what I'd do. I am curious about what it looks like so if you can email a picture that would be great.
Good luck,
Gary.