spindle worn,maybe wrong bobbin put small piece of paper between spindle and bobbin if you want quick fix,or if your spindle is one that is cut in 4 pieces at top you can insert something like a match in center to give it more body,spindles are normally cheap and easy to replace.also check winder rubber running against handwheel,may be cracked or flat spot,put drop of oil on spindle shaft to let it run free
johan
September 2012