That is what happens when the slam switch is activated. It's normally closed, so being disconnected isn't necessarily a good thing. There is a mod you can do to solder it closed. You may have a switch matrix problem or it may be a diode or something is physically touching that shouldn't be. Keep digging you are doing well!

The switches for the slings that the cpu sees are underneath. The leaf switches you are looking at on top are likely not the problem. That arcing is normal. Take a peek underneath and activate them and I bet it slam tilts. I think there may be more than one slam tilt switch, I think there is one under the playfield too but I am not 100% sure. The "rubber switches" don't seem to line up with anything on the switch matrix on page 40 of the manual. hmm. Does hitting any of the other rubber switches tilt it or just slings? There is one by the upper right capture light.

Right on. Does it slam if you bang on the playfield? I think the scoring switch for the pop bumper is on the switch stack underneath and unrelated to the pbdb. I could be wrong, I haven't been under there in a while.

ps what botango said