I doubt if you broke it. Look at the silver stop motion knob. There is a hole on the end of it and there should be a screw in it. Is the screw there? It is a stop screw for the knob so that it won't unscrew too far. If the screw wasn't in all the way or if it is missing, it is likely that the washer underneath that knob fell out of place. It's an easy fix and if the screw is missing, you can probably get one from a local Sew and Vac place. Here is a link to a repair manual that shows how to service and clean the balance wheel:
http://www.tfsr.org/pub/technical_in...ance_wheel.pdf
All you probably have to do is remove the silver knob re-install the washer and then put back together. On some machines (and I'm not sure about yours), the washer has to be installed in a specific way in order to release the clutch when you unscrew the knob. Sometimes, you might have to flip it or turn it 180 degrees to get it installed correctly.
Good luck.
John