ELNA SUPERMATIC Rubber Pulley Replacement for Flat spot

Elna 722077 motor pulley replaced due to flat spot. Green Elna in video is a 1952 model 722010; Beige model in video is an early 1963 722010. The 1952 Green machine here has the older type coupling knob; the 1963 has the newer style coupling knob a retaining ring. The coupling knob is what one disengages the flywheel to wind a bobbin and reduce the pressure on the rubber motor pulley when the machine is not in