Vintage Sewing Machine Parts - Stitch Pattern Cams

When I bought the Empisal sewing machine, she (I've named her Iron Beauty) came with a retro container filled with plastic knobs. There was no mention of these knobs in the manual - which is a scant document - so I asked a few friends. The consensus was they might be attachments altered the stitches, in order to do decorative stitching.

After googling I was pretty sure they were correct, and in fact what I had was a box of plastic Cams, also called 'stitch patterns'.

However, google has really let me down (for the first time ever). There is next to no info about the Iron Beauty and her Empisal family. But after much searching I saw a grainy low quality video where a cam was put somewhere on top of a vintage Singer.

So my next step is open up Iron Beauty, but as I couldn't figure out how to thread her without the manual, my hopes for this mission succeeding are not high. Possibly the box of cams isn't even for this machine. We shall see...

UPDATE I have figure out how to use the cams! READ HERE

Vintage Empisal (Brother) Gold Line Sewing machine & plastic Cam stitch patterns