I guess I joined this forum back in 2018 when I dove head first into quilting (again). This time, I'll actually share somethings especially my newly acquired Singer 15-30 which I'm going to play with, care for, and use to my heart's content. But first, I want to share a link to a video (hope it works) that saved me. I got too excited and disassembled the bobbin winder and watched its springs, spring out. (If the link does not work, just look for "Singer 66/99 bobbin winder jigsaw puzzle" by Ray Elkins on YouTube.)
https://youtu.be/vExPGb34JFM