Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Brother sewing machine parts may be had from a variety of sources.
As for the screw - is that the Tension Screw, like the one on this page?:
which lists as $3.59
(minus shipping, tax, etc.)
and which the heading of the page says is guaranteed to work in an LS1520 machine.
There are also on that page, two Bobbin Cases, both part # JO1313Zx and they are listed as $ 8.99 and the other one $ 12.99.
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