OK, so this would normally be OT for this forum and maybe on-topic for a Good Housekeeping forum, but it has to do with car upholstery on a pre-1964 car. Decided to DIY a small armrest upholstery job that should have been a no-brainer. Wife has a small Sears sewing machine. I bought some vinyl. We're using button thread with a denim needle. The vinyl walks through nicely and the needle pierces easily. The problem is that it won't stitch. It seems that the thread isn't being pulled through. My wife demonstrated that the setup will easily sew denim and even a piece of thick paper card stock. It makes a nice row of holes in the vinyl, but no stitches. We tried it rightside-up and upside-down. Any ideas why this is failing?