Janey, thanks for the photo of the winding mechanism! I was able to use it to carefully compare to the winder on my Singer. The pivot point and adjusting screw are further back on yours than on mine, and as a result the roller on yours is further back than mine. After more research online my suspicion is that the winder on mine is from a 1950's era Model 66 and not the original 1921 Model 66 version. I suspect the later versions moved the winder further forward to accommodate solid handwheels designed for electric motors. As luck would have it, there was a 1921 bobbin winder on ebay yesterday which i purchased to confirm my hypothesis! It looked to be in rough shape but I'm hoping it's just dirt and surface rust and will work after cleaning it up!