Well I was looking for a darning foot for my SWA 2000 and came across this posting. Not sure if the cam questions got resolved but I have had my SWA 2000 since 1974 and you do not need a cam to do the zigzag stitch. You just have to be sure and use the correct pressure foot. Also when using the cam be sure to turn the zigzag width knob to the right, insert the cam, turn to click in place then release the zigzag width knob. Then you are good to go.