Do you have a manual for yours?
https://www.manualslib.com/manual/86...inger-237.html and
https://www.singer.com/support are places for manuals. They might be the same one.
I may have gotten the position of bobbin winder tension backwards. I have a manual that I got in an old Yahoo Groups that says it from 1967 and shows the bobbin winder tension in the middle of the arm.
Janey - Neat people never make the exciting discoveries I do.
Not affiliated with off-site link(s)
ETA that I forgot to add links in previous post for images of the part
https://www.vintagesingerparts.com/c...9-parts?page=3
https://www.bonanza.com/listings/Sin...2021/218549475