This may or may not make you feel better, but the first vintage machine I rehabbed, a Kenmore from the 1960s, I ended up with a screw at the end and no idea where it came from, and I never figured out where it went, but it didn’t seem to matter. It worked fine, at least while I had it. Here’s hoping that if you can’t figure out this mystery your machine will be equally as functional without it.