When you set your vintage Singer sewing machine into bobbin winding mode, by cranking the stop-motion wheel counterclockwise, the needlebar is supposed to stop running. This is to save unnecessary wear-and-tear on the machine, and prevent you from having to unthread the needle to wind a bobbin.
However, if a few crucial parts of your machine are dirty, the needlebar will continue to move even though you are in bobbin-winding mode. This is easy to fix, and I've made two relevant videos, below, to assist you.
