OK, it took me a while, but Mission Accomplished!
Following along with AndyTube's videos on a Singer 403A (he calls Regina), I took off a ton of parts, cleaned them, cleaned the main body in the shower, oiled and greased the frozen (due to the super, degreasing cleaning) gears, put all the parts back on, and it runs!
No, I haven't tried actually sewing yet, that's next.
Thank you for all the help when I was asking questions here when I started.
Btw, I have one small screw left over after reassembling everything. A special super "Thank you!" to anyone who can figure out where it belongs! (please see the second photo below)
