Long story short - I bought a Big Deal a few months back that had been sitting for who knows how long. It's my first EM. Dug in, got some things fixed on my own, and with the help of a thread :
https://pinside.com/pinball/forum/topic/williams-big-deal-1977-score-reels-not-resetting
was able to get it up and running 100%. Took it to MGC where it got through 350 or so games before it had a score reel coil die.
Got it home, replaced the coil, fixed an issue with a playfield switch being stuck on, played a few games, replaced a flipper bat (with the help of a very generous pinsider.) and then played a couple dozen games. All working fine and without issue.

Went to play the other day, and something's gone wrong. When I press the start button, the score motor turns for about a second, and the coin unit stepper steps. But any score reels not on 0 don't reset back to 0.
Since I had the machine on free play, additional presses of the start button add additional players - repeating the above even when the coin unit stepper is on 4 players.

The reset cycle from the manual.
reset-sequence (resized).jpg

I've tried to follow along these sequences, but my inexperience is tripping me up this time.

Any ideas on where in this sequence things are going wrong? I mean, since the reels aren't resetting, I assume it's something in the first four parts, but I'm sadly lost. If I manually trigger the reset relay, the score reels will reset, so if I'm reading things right, I assume it's actually something in the first three parts.

Anything I can test and report back with to help with diagnosing? I do have a copy of the schematic from PBR - it's on ipdb as well.

Looking at it more - as I mentioned, the score motor does turn briefly when I hit the start button. I'm assuming that this is the "run score motor" in the third part.

The reset relay doesn't energize though.

Not sure what's going on with the game over relay. Am I understanding this relay right?

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I'm still going to post this, but pretend those dots represent around about 20 minutes of this reply window being open while I went and read some things.

Then pretend that I read about the game over relay. (I did)
Imagine that this site has once again helped someone. http://www.pinrepair.com/em/index3.htm (It did)

In particular :
"Bally and Williams games often use a latch relay for the game over circuit that has one switch which controls all coil power to the game. If this one switch is dirty or mis-adjusted, the game just won't work! Clean and check the game over relay switches"

Went through the game over relay - all the switches seemed to be adjusted right. Two make breaks, to normally opens, and one normally closed. But 2 minutes of running a burnishing tool through the contacts and everything is right as rain.

Thanks for all of the responses that were going to get me out of this jam, but I got this one.