One of the problems beginners have with sock machines is setting up the yarn supply to guarantee zero back tension. It looks as though one could simply feed the yarn from a skein, ball, or cone directly into the machine. Sooner or later, the yarn will snag, and that happens when the heel is being turned and the last needle to knit is at a critical position.
       The manufacturers of sock machines recognized this from the beginning, and nearly every manual included a paragraph on the importance of winding the bobbin. Admittedly, some yarns feed well from the cone, but seldom does a skein or ball give trouble free performance.
       The instructions below are from a Gearhart Manual. There are some new innovations involving the use of paint rollers, etc. that look easier than winding a bobbin, but they don't improve on a properly wound bobbin. The coat hanger/ paint roller device I designed might be OK, but is not as good as a well formed bobbin.