Rumor has it a battery is not needed but I do know that if a RAM chip is not working you get a RAM error tilt.

Nice work David. I've was eyeing that machine also. Was waiting for the guy to reply and got some story that he just got out of jail, machine is worth its weight in gold & knew what he had, etc. I was going to keep working on getting a decent price for it but I just decided the guy seemed flaky and I really didn't need the machine. I had plans on restore like what you are doing. I've done a few that had a lot of rust and completely striped them down, painted all the parts etc. Its a lota work but worth it and very rewarding. By the way I've contacted you before here locally and you told me you had no interest in slots with MPU boards and only liked restoring EM machines. I am out here in Big Lake. I got a small pile of S+ parts. I may have something you need or vise versa.  I get some molex stuff from mouser.com

Zip-tie them back up into the door harness.... you may not need them.
The harness with the black Molex, is for a multi-line reel glass display panel.
The other smaller harness with the rust-colored connector is for... I don't recall what it's for, but you don't need it right now.

Putting it back together.
I have a couple of plugs on the door that don't go to anything. 

MPU service.