I have a question regarding my 40 year old Elna sewing machine bought in 1969. V/NV/21, Type: 21cF347986?

Take the band off and buy a new one..Be sure it is not set for bobbin fill.If the band is tight, you may not need a new one.the attachments come in short shank and long shank.Check at a sewing shop for the size you need.