I forgot to mention that I replace the bobbin case and the bobbin from a newer Singer sewing machine I had and the thread still breaks when I try to sew. It might be catching on the feed dogs. I tried to getting the screws loose but they are tough to get free. I've cleaned the tension spring with alcohol and feed dogs with a toothbrush done all the oiling. I think I am threading it correctly. I've checked youtube about a half dozen times on threading Singer sewing machines. I have the flat part of the needle to the left.