Nancy's Notions has bobbins for these machines. Also feet for the Slant Needle machines. Don't be afraid to adjust the lower tension, although this doesn't sound like a tension problem, possibly something to do with the needle or pressure foot adjustment. What model are you working on? I can't picture picture what you're describing. I have four of these units -- all working, three 600's and one 648 (think that's right). Have never had a problem with anything like you suggested. Hope you find a solution soon.