I picked up a used Brother 1241. It sews well, but the dial to move the stitch selection has fallen off, so I am only able to use the straight stitch. I am unable to use the Zig Zag stitch. I have the front piece dial and the spring that goes behind it but do not know how to re attach it. Can you tell me if I am able to do this myself. Are there any extra parts that I would need? Thanks for your time in advance.