pull out that manual and read where it shows how to check for threads and lint in the bobbin area. Also check that you are putting bobbin in correctly so thread coming off in right direction--I know you were doing fine before, but sometimes our brains fool us! Now, rethread the top thread, making sure that you have the presser foot up while doing it so the thread "sits" in the tension discs. also make sure that you have the needle in correctly--sometimes when we don't we'll get the problems you describe. Good luck!