How do I replace the needle on the XH2135-001?

Turn off the machine and loosen the needle clamp screw counterclockwise. Insert the needle with the flat side toward the back of the machine until it touches the stopper, then tighten the needle clamp screw securely with a screwdriver. Make sure to insert the needle completely until it touches the stopper to prevent it from breaking or damaging the machine. (Page 1)