I got one!
My grandmother and mother taught me to sew on a treadle sewing machine when I was 9 years old. Always wanted to have one again. We found one on a tag sale, model no AC765383, which puts it in the 1929 age range, I think. Someone started to strip the cabinet so it will need to be refinished. It does sew but is really sluggish so I know it needs all taken apart and cleaned and greased. Also some of the black finish on the front edge and a few other places has worn thru and needs attention.
Where would I go to find out how to do all this?