Robert, it looks as if this assembly is very similar to that on the 115. The little knob on the knurled thumb nut is not the indicator, rather, the window on the short cylinder gives you a place to view the compression of the beehive spring. That knob is a device to adjust the fit of the thumb nut to the mechanism, allowing one to adjust to get a full range of tension, if numbered, from 0-9.
I'll have to resize a photo to post here, I do have a photo with the 115 sequence. I hope someone beats me to it!
ETA: nope, the recent photo I found is from a a 1936/37 15-91 with nickel plate stitch length plate. I'll have to look further for the 115 project.
I learned the hard way, too, to carefully disassemble, layout the sequence, and take a photo. But then, that assumes the person who messed with it before me installed it correctly.
Last edited by WIChix; 02-24-2021 at 05:35 AM.