All good answers from everyone! I recently gave my singer machine to my DIL and told her it was a little quirky and sometimes and did this same thing with the thread so don't get frustrated (she's a non-sewer) and to try these same suggestions. My (mechanic) son called me that night and and proudly announced he fixed the problem and that it was running GREAT! He then told me he found this little screw on the bobbin case that was "loose" so he tighted it up! I gasped in horror imagining how "tight" a mechanic would do a screw. I quickly told him no no no this is not like a car! you may need to loosen it a little!! I laughed about it later.......