These old winders are amazing machines, but the cams and gears are extremely hard to source! I was lucky enough to get two nearly complete machines and gear sets, but cams were a different story.
I designed these to fit the shaft on my Geo Stevens 39AM and 38AMI but they'll fit any other Geo Stevens winder and likely any other brand that uses a 1/4" shaft.
Included are the STL and DXF files, I had mine cut by a CNC company in Acrylic and have been running them for almost a year with no wear.
248 for standard humbucker bobbins, 452 and 468 for Strat and Tele, but those are the widths I use, your's may differ.
Video of the Cam in action: