If, like me, you've had trouble getting your head around just what goes on inside a sewing machine; these vids may well be of help...
Secret Life Of The Sewing Machine Part 1
Secret Life Of The Sewing Machine Part 2
Secret Life Of The Sewing Machine Part 3
Secret Life Of The Sewing Machine Part 1
Secret Life Of The Sewing Machine Part 2
Secret Life Of The Sewing Machine Part 3