The needle is not in alignment with the feed dog hole . The clamp screw to undo the needle bar in the rock frame is behind the little plate next to the reverse lever if I remember correctly. Loosen that screw and then you have to slowly by hand turn the wheel towards you which will make the needle descend. You then center the needle in the feed dog and tighten the clamp slightly. Turn the wheel again by hand and check the alignment. If good, tighten the clamp. However, you have to make sure the feed dog is correctly positioned before doing any of this.
glenn