Pinkberrykay,
My machine looks just like yours, except mine runs on treadle power, great machine.
The 237's needle goes in with the flat to the right and threads from left to right. It takes class 15 bobbins, the bobbin goes in with the thread coming over the top toward you. Make sure that you have the take up lever all the way up before you take your fabric out. Make sure that you have a new needle, takes a 15x1 needle; I use Schmetz needles.
Check for burrs in the bobbin area and also throat plate.
I have pictures of my 237 here:
http://good-times.webshots.com/album/578828743YiOtbl
Sharon W.