It's possible that the bobbin casing has somehow come loose and would need to be adjusted by a repair person - just a thought. I own a Brother PC-6500, which I've had for four years and it has never given me a bit of trouble. It's also an embroidery machine. Unfortunately, it has been discontinued, but if you are having that much trouble and frustration with a machine, you could have it looked at - or - but a new one!! :)