Two days experimenting with Slip Plate graphite spray. Another day to apply six coats of graphite to the existing substrate. Voila:
https://picasaweb.google.com/lh/phot...eat=directlink
The schematic specified 2.5K for the volume rheostat. Started with an erratic range 20K-to-0 ohms; finished with a smooth, linear 2.7K-to-0 ohms.
Thanks to my mentors and collaborators--we've saved an original part that would have been quite difficult to replace.
-Winky