Getting this old gal to purr like a kitten is almost complete, I'm happy to report.
Final stitch length per number on the dial was a little bit of a pain, thanks to a bent needle. What I posted earlier about it has stayed true, so I have a wide variety of lengths to work with now. Also cleared up a previously unnoticed issue with the zigzag, when I started working out the lengths, I decided to test the zigzag again and realized I was only able to get one size. I worked the knob and mechanism the same way I did the stitch length and happy to report, I've got all five zigzag lengths.
If anyone is reading this that recently got a hold of one of these machines and can't figure out where the reverse button is on it, it's the actual stitch length knob, just push it in and hold it for a few stitches, then release it and it will continue to sew forward. Mine still felt a little gummed up, but after some oil and pressing and releasing the button, there's been no more issues.
I went on a more aggressive clean and oil yesterday, can happily report there's no more fuzz, lint or gummed up anything inside the machine, when I stitched up the swatch to show the stitch lengths, she was just humming and stitching along with no hiccups. Aside from that small spot of rust on the bobbin plate, this little gal is cleaner than she's probably ever been since she came off of the assembly line. That felt deeply satisfying.
Interestingly enough, this is not a Singer, I got in contact with them via email and had a very lovely exchange with one of their support personnel. I've checked all of the sewing machine manual websites that I can think of and no one has this manual so I'm now down to contacting the manufacturer, who looks to be a company called Euro-Pro. I'll do that this weekend, I've been fighting a small swarm of migraines that's kept me from getting all of this done.
Unless I'm forgetting something, I'm calling this project done. It's been a hair raising, hair pulling experience, but I wouldn't trade a second of time for anything else. I love this old girl, we're as thick as thieves now.