Standard is rather unique. I'd have to recheck for sure, but I'm pretty sure that the attachments and bobbins are different than for any other machine.
While I don't have a machine like yours, I do have an original manual. I think I got it with a set of attachments.
Can you take some detailed measurements of your bobbin? I have several for the older Standard rotary bobbins, but have no idea if this machine takes the same. Like you mentioned, the manual isn't very helpful- like with the needles, it just says "Use Standard" and nothing else. I like the ones that show a full size drawing so you can match them up.
This machine was made after Osann took over Standard