Rose, by looking at your photos, it seems that it was wired correctly, but that one of more of the wires came loose off of the contact. If it came lose from jiggling it on and off the machine, it likely was just not wired stable enough. You can redo it and just make sure you screw them in tight. And in the future, just be gentle putting in on and off the machine.
These are great controls and I would never want any other type controller on any of my 301's.
I don't see a problem with too much copper showing. This is typical. I can't really see any burned areas in your photos.
If you want me to Rose, I can take apart one of my controllers and post a photo, but it looks like it was just lose wiring.