My throat plate is rectangular and the pillar is somewhat square with curved corners. There is a round access hole about 3/4 of the way up with a circular plate over it in the pillar. The belt goes on the inside of the handwheel. From illustrations its looking like it might be a New Home 914 or 915 but I haven't found photos of those machines to compare. The single thread post is near the top of the pillar and not midway across the horizontal section.
I may see if I can link photos posted elsewhere as I have no upload icons at all, only a post or reply the thread icon. (Possibly because I'm new? I'm wondering if you have to post x number of times before that privilege is granted?)