Hi, thank you for contacting JustAnswer.com. My name is Russell. I feel that your question deserves an answer, though you have evidently found a solution elsewhere.
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Did you drop the bobbin screw into the inner workings of the machine?
If so, that is best retrieved using a magnet on a stick, or a tweezers, or a forceps, or any similar instrument.
If you cannot retrieve it, then unless you are in a great hurry to get the machine working again, it might be better (provided the screw is genuinely down deep inside the base of the machine and will not be caught in the works anytime) to simply order a replacement for that 'bobbin screw' (I'm not sure what a bobbin screw is, to be honest... let me know, please.)