Replace the movable and fixed knives
- Loosen the two bolts (1) and then remove the feed plate (2).
- Open the hook cover, remove the two screws (3) and the two flat screws (4), and then remove the needle plate (5).
- Remove the movable knife (6) and the fixed knife (7).
4. Install the new fixed knife (7) in the position shown in the installation.
5. Apply grease to the outside of the collar (8) and to the shoulder screw (9), and then install the new movable knife (6) together with the thrust washer (10) and the movable knife spacer (11).
6. Check that the movable knife (6) and fixed knife (7) cut the thread clearly. Replace the movable knife spacer with accessory spacers (t=0.2, 0.3, 0.4) so that fixed knives trim the thread accurately. (If the knife pressure is too weak and the thread is not completely cut, use a thinner movable knife spacer.) and (If the knife pressure is too strong and the movable knife (6) turns stiffly, use a thinner movable knife spacer.)
7. Apply grease to the pin (12), place it into the movable knife connecting plate (13), and install it to the needle plate (5).
8. Check that the needle is aligned with the center of the needle hole.