Suggest you clean inside and underneath bobbin area by removing the bottom cover. See video;
https://www.youtube.com/watch?v=cdTmAJSq4i8
Just remove first two screws and cover. You won't need to get into the other space. As the gentleman said, "be careful there maybe broken needles". Look for any screws or other parts that may be in with all lint, fabric, and whatever else you might find.
If necessary use a vacuum to suck out all the lint. Do not use compressed air. Use a clean vacuum bag and keep the vacuum bag in case you find later there's a missing sewing machine part.
HI, there are a few reasons for this. Make absolutley sure your needle is threaded correctly. (I've been sewing for years and this sometimes happens.) Next, make sure you have the correct tension for the thread, and the material you are working with and of course the correct size needle and not an old one.
Sometimes the thread is old and it minutely frays and knots, or the needle is blunt. And finally, make sure there is no thread tangled underneath. Hope this helps.:-)
Check how your thread is coming off of your spool of thread. If it is older thread it is wound on the spool differently than a modern spool of thread. The older types of spool were would to pull off of the spool from the side. The newer thread is wound so that the tread needs to come off the spool from the top.
There is between two and four screws on top of the machine. Remove them. Pay attention to the bobbin winder. You may need to move it in order to get the plate to be released.
