I agree with you, after looking at needlebar.org, that it appears to be a National Improved Seamstress. I can't help you find a manual, but if you post a picture of the front/nose of the machine we might be able to help you figure out the upper thread path. Loading bobbins and getting a bobbin in the shuttle, etc is going to be very similar to other vibrating shuttle machines, along with picking up the bobbin thread. Put a piece of cloth under the presser foot, with pressure on the presser foot, and rotate the hand wheel by hand, in both directions. Whichever direction has the cloth moving away from you is the correct direction of rotation.