My sewing machine has been acting naughty lately. The bobbin gets all messed up for no apparent reason. Finally, I unscrewed the plate and took out the bobbin holder. Dear God, there was a lot of lint in there. Like pounds of it. And it was packed into solid formation like this lint here, which I broke in half. That's right, I broke lint.
I used a little brush and some tweezers and got most of it out. Then I used canned air to blow everything else out. No wonder the little cogs and gears couldn't turn properly.
After I put things back together and resumed sewing, it purred like a kitten. I hadn't realized that it wasn't supposed to sound so loud and clunky. I had to actually stop and check that it was really sewing because it was so smooth and quiet. Yay!