Today was pretty momentous for me- I'm done soldering! The entire underside of the playfield is back on, and all of the flashers, coils, and the switch that are on top have been soldered and screwed back in place. I polished and re-assembled the trough and got the apron back on. All that's left are the wooden rails, wire-forms, and the plastics and wire guides. I could finish tomorrow, but I need to order ONE freakin' 6-32 post. I thought I already ordered it, but either it got packed wrong or I ordered wrong because I have an 8-32 instead.
As for that wire guide mentioned above, my best guess is that it was meant to prevent balls from getting lodged behind the rubber there (by preventing the ball/rubber from stretching that far). That's all I can come up with.