Riccar Model 15

Question

Hello! I own a very old Riccar Model 15, which I recently had tuned up. It runs great -- But the operator's manual has long since been lost. I'm not quite sure how to thread the bobbin or wind a bobbin (only vaguely remember, as I last used it 30+ years ago!!). Any suggestions? Or do you know where I could get a copy of an old manual? Thank you!!
Audrey Barhite