I've seen union local stickers within Bally EM pinball machines I've owned. An old-timer told me those were the only union-built pinball machines.
I find it interesting that people here want to know EVERYTHING about the current manufacture of pinball machines but bristle at this line of investigation.
I'd be curious as well about this type of information. It's not like it keeps me up at night, but hey, folks are just asking questions!