Singer 211G256 266 Manuals
You can see here it explains the differences between the two machines + what the button on the top does!
Couple of manuals I have in my library for you, the 45K parts book shows how the clip goes of the wheel, I remember now it’s to hold it up out the way when not in use, up to the right away from the needle. see images on page 5 and 33 you can just about see it there.