http://www.ismacs.net/singer_sewing_machine_company/manuals/singer-sewing-machine-manuals.html
Ismacs is an excellent resource for free manuals and helping you identify a vintage sewing machine.

I have several manuals, probably more than a 100, but that is a few thousand short of what was published. If I can help with one, I'll sure try. I was hoping to copy and load them for viewing, but there are many sites out there already and it is a real time consumer.