Brother S-7780A Instruction Manual page 60

5. CLEANING
51
<Cleaning>
1. Push the release lever (1). (The upper knife (2) will rise.)
2. Raise the presser foot.
3. Remove the two screws (3), and then remove the needle
plate (4).
4. Use a soft wire brush to clean any dust from the feed dog
(5).
5. Install the needle plate (4) with the two screws (3).
1782D
S-7780A