I have a second hand Janome sewing machine. It is a mechanical model with two dials which show a variety of colour coded stitches. These are: a white set of 1 straight and 4 zig-zag stitches of different widths; a green set comprising a 4 part buttonhole; a blue set of 7 fancy stitches with an automatic feed (ie needle and feed move independently of the operator with multi-strokes to each stitch); and a red set of 5 fairly straightforward pattern stitches. Under the lid there is also knob which has 3 settings (1, 2 & 3), the 3 is enclosed in a rectangle. Would anyone be able to identify the model and hopefully point me in the direction of an operating manual. Failing that can anyone explain the use of the knob under the lid?