thank you to miriam and cabbagepatchkid, I now have my 15-91 sewing like a champ! and have a pdf manual.
My DH is going to rewire the cord and foot control as it is patched in three places and needs a fourth up the machine. It could stand to have 2 more inches in length to the foot control just to fully touch the floor from my low sewing desk. (and I'm short!) the manual told me I have all the original assessories/feet for it also. Good buy for $50 at a garage sale I think. thanks again. I'll be checking in every now and again.