Help! Missing Unknown Part Sewing Machines Parts and Sales in Los Angeles

I've recently acquired an old Brother XL5340. My grandmother bought it at a garage sale awhile back. The machine looks brand-new and it's in really good shape. However, the needle holder won't stay attached or in place. I'm thinking it might need a tightening scew like the one that the needle is using to stay secured. I found a place online that has Brother parts, i just need to know what's it called.