I have a circa WWII Model 15 clone badged White that looks very much like this and threads the same way. However, here there is no stitch length, no control to drop feed dogs, and are there any feed dogs? It looks like it has a dedicated hopping foot and a thread guide for yarn, perhaps. I'd guess that someone started with a Model 15 clone body and modified it in a professional machine shop. I think this machine has lived it's life in a sewing production shop and had only one job.
Cricket