I also have an old Singer in a bentwood case also, my MIL gave it to me. it was what she called her heavy duty machine, I haven't used it yet, but plan to try it out, when I attempt a blue jean quilt as you go quilt, one of these days. I've been collecting jeans for years. I also have an old Singer treadle that I bought in 1964 at a Salvation Army store for an ad re: antiques. I used it some, way back then, but haven't used it in years and it needs new belts and I don't know what else, I'd love to get it repaired, and give it a try.
Actually,what I sew on regularly is a 1964 Kenmore (all metal machine) Is that considered vintage, yet? It's a great machine.