I think the stamped # on the frame is H151522 instead of 757522, gotta go check that out. Just oiled and cleaned it up and run a test stitch....PERFECT stitching....I'm doin a "happy dance". And thanking my momma for hanging onto it all those years.
I bet it's a 15-91 Singer, sure looks like that one, printed a new manual.
Viv
Viv