No. 29 - Retainer spring
Usually ships within:
Hint! Refit the needlebar retainer assembly by placing the retainer spring in the groove of the needlebar retainer. Push the retainer fix screw trough the first hole opposite of the retainer bearing side, trough the retainer spring and into the second hole. Leave the retainer fix screw end flush to the needlebar retainer surface on the bearing side. Put the needlebar retainer assembly in the groove of the frame and slide it back into place. Make sure that the end of the retainer spring engages correctly with the groove in the frame. Hold it in place while tightening the retainer fix screw.