I've recently moved into a building that has a Singer 120u industrial sewing machine. This machine is like a machine gun for sewing. It has little guards on places where fingers could easily get snipped off. It also has a complicated and highly configurable threading system that works by friction on various metal plates and poles.

I can't figure out how to work this thing, because the thread keeps breaking. I've played around with some trial and error, but I'm not grasping something fundamental to the setup.

Where can I find instructions on how to use this wonderful machine?