I'm not sure I'm understanding your description correctly, so please forgive me if my answer is inappropriate... I have a very basic Brother machine. The screw head butts right up against the needle holder thing, too... but it unscrews. Then I put the walking foot on and screw it back in, and it holds it in there. According to this page on the Brother website, the same walking foot (SA-107) fits your machine:
http://www.brother-usa.com/homesewin...7#.TzJ2SflSySo
I was able to find my walking foot on Amazon.
http://www.amazon.com/Brother-SA107-...dp/B001UZ118O/