Hey, I actually just stumbled on this thread while searching for bobbin tension suggestions for my singer 401A! I am doing some sewing for the first time in years on a used jumpsuit I just bought. The lady at the sewing store suggested "Topstitch" Needles. The eye is slightly larger, allowing for the nylon thread I'm using to work in this home, non-industrial machine. I still haven't gotten my tension right, I've got the top thread tension all the way up, so, I'm working on the bobbin, but it's close
