This piece is the equivalent of the set screw on the 66, I believe.
Check spring I n this photo you can see that the check spring is sitting under the thread guide. You want the check spring to be positioned between the two indentations on the opening in the machine
More like this.
I could not exactly remember so today (1/31/12) I got the machine out and took it apart again and figured out what I did.
I took the stud and the check spring out and looked at them. I noticed that the check spring has a smaller loop at its proximal end (the end that is nearest the body of the machine) That small loop needs to sit on the proximal end of the stud so that when the stud is tightened the spring is held fast and able to bounce in between the two indentations as seen above.
Inevitably as I tightened the stud, the check spring would tighten in the same direction and end up wrong wrong wrong. So I fiddled. I loosened the stud and pulled on the check spring very gently:
The next photos are from the original post. I can't change them at this point.
The tension discs are placed so that the convex sides face each other. I tried to get a good shot of them.......Not in focus, I apologize.
Tension discs in place. They are clean, just stained. (Sort of like my fingernails)
Next comes the tension spring.
Here you can see how the check spring should be positioned at about nine thirty. It must be correct because the stitches are just so nice. I just fiddled with it (see above) and the stud until it looked like the tension assembly on my 27.
This post has been updated from the original on January 31, 2012 thanks to a question from Carol from vintagesingers yahoo group. I appreciate her question because it makes this post much more complete. I also had a chance to fool around, some more, with Adobe Photoshop Elements 10. Software that came with no manual. Jeez.