Oh my, that is frustrating. A trick that I learned is to totally unthread your machine, and then remove the bobbin. then work the needle up and down to see it still feels "sticky". If it does, I would change the needle, and try it again. sometimes tangled bobbins put barbs on the needles that you cannot see. Try this simple procedure and see if it helps. Did you remove the bobbin cover plate too? Systematically trying little things can help. Good luck,