The Brother home sewing solutions support center can be contacted at:
7777 North Brother Blvd.
Bartlett, Tennessee 38133
9:00am to 5:45pm Eastern Time
They don't list the spool disc part specifically on-line, rather they show accessories you might purchase - but your manual should list the part in the parts diagram, the manual is located here:
The Brother service centers, which could also provide your part, are listed here:
I couldn't look up the one closest to you because doing so requires your zip code!
Hope this gets you on the right path, if you appreciated this information, could you please be so kind to take a minute to rate this solution for me? Thank you!