into the backglass we go!

One more place gets a cursory examination, the head!  Or Backglass.  Or Back box.  Or whatever.

They keys for it were in the coin box.  Shall we?

oh you were spray-painted with a stencil, weren't you?

Turn the key, lift up and out, set the metal backing down, and...

simple!

top left we have the 4-player score reels.  I think the score is actually counted by a mechanism under the playfield, these just rotate.
Bottom left, that unit is the credit counter.  It is a wheel that goes up to 15, because apparently back in the day pinball wizards could rack up multiple free games.
I think the thing to the right of it tracks which ball it is for each player.
I have no idea what the things on the right are for.  Matching?  I'll check the schematics in a later post.

The things to adjust back here are, once again, clearly labeled.   The main thing to control is when to award replays.

There are actually loose wire-pins with 0-9 flagged on them.  Each of them has 2 points.  You grab one, insert it in to the offset hole, and then in to another.  I'm not sure if you can use 2 different wires for 2 differentiating replay scores, but I used the same wire because it was attached twice when I got it.  I set the score for 90,000 and 99,000.  Hitting those marks would award a free credit.  It takes some serious concentration/luck to hit 90k, and I couldn't imagine doing it with the original tilt intact.
Most of those blue wires you see are going in to the plywood, not connected to anything.  Their plugs are just there for future use.

That thing on the bottom right is a big ole connector you can move for 3 or 5 ball play.  Anyone who would set an EM for 3 balls has already been disposed of, so no need to tamper with this.

ooo a hole!

This part is important, especially for later discussions of moving a pinball machine.  What we see here is where the head attaches to the body.  4 easily accessible bolts, and 4 easily removed connectors.  If you've ever done anything on a motherboard, these by comparison are as hard as inserting toast in to a toaster.
Hands-down, the EMs are the easiest to disassemble and move.  Unplug the connectors, feed them in to the body.  Remove the bolts.  Head is OFF, and since it holds almost half of the weight, the moving job is simplified greatly.