My husband bought a 403 Singer at an auction that had no cords, very dirty etc . in a cabinet for $5.00. I cleaned her up, got the cords, got it to stitch, does a pretty good job. My question is, it has a zig zag cam in it but it does not zig zag. There are no other cams with it either. Any idea about on what might be the problem and should I order more cams. Don't want to if it will only straight stitch. Thanks for any information.