If the 300/3 Advance Relay still wants to pull in after you manually open it, its seems maybe
a stuck switch on the playfield. I took the Captain Fantastic down for now, but there's a couple
rollover switches (A & B) that activate the 300 Point/ Adv. Relay. If you haven't already, I'd check
those switches along with its solder tabs..

I checked the schematics, and like Timme stated, the "Inner Right
Bottom Lane Switch" is a direct path to the 300/3 advance Relay without any
other contacts needed to be made. Maybe the solder tabs or even a super thin
steel wool stran. I once had continuity from one blade to the other on a Ball Bowler
wiper, yet an insulating spacer was seperating the two. I ran a razor blade knife a
couple times between the blades on top of the spacer's edge, and that did the trick.
I also had an insulating spacer between blades somehow fail to insulate, so crazy
stuff beyond the naked eye can happen..

It almost sounds as though the 10s and 100s score reel are energized and pulling in
the coil, then when you shut the game off, the coil releases spotting #1
The question I have, is when turning the game off, why are the score reels on 0, because
you're resetting it first, and then turning it off?

Yes, if you manually activate the Game Over Relay, it cuts the power to the Score Reels
which would be the same as turning off the toggle switch.
If you start up a game, then manually step up the Player Step Up Unit so it's on Player 2,
then turn off the machine, my guess would be the 10 and 100 would step up on Player 2
as it does on Player 1.
I'm thinking maybe a couple stuck playfield switches. After starting up a game, you can
check in back of the head if the 10s and 100s Score Relays are energized. I guess it could
possibly be one playfield switch, but then I would think another make/break switch under
the playfield that transfers the scoring from 10 points to 100 points is making together.
I would maybe first check if the 10/100 Score Relays are energizes after start up..

Yes. So it seems the 10s and 100s score reels are getting juice. When you step up the Player Unit to the
next player, it de-energizes the previous Player's Score Reels and the coils then pull out and chalk up the
number, so it sounds like the 10s and 100s Score Relay are energized. Sorry, I forgot. Is this Captain Fantastic
you're working on? It seems the chimes would be energized also, and I wouldn't think so, but maybe somehow
the Score Reset Relay is the one being energized, but either way, I'm surprise you can't hear a coil being stuck
on. You don't want it stuck on for too long. When you try it again, perhaps you can check if there's a Relay that's
staying energized. I would think it would be one of the Relays in the head..

Yea, I rechecked. A Captain Fantastic you're working on.
It's been awhile since mine's been set up, but now I do remember the
Thumper Bumpers lights do alternate. The center switch of that make/break
should only be touching one or the other of its outside blades, so you'll have to
adjust that so the center blade is touching only one when it's energized, and
the other when it's not energized..
So not any of the Thumper Bumpers are energized, but one of its sets of blades
underneath is touching. You'll want to adjust that blade so it's open like how they
are on the other 2 Thumpers (assuming the others are okay). That set of blades
should only instantly touch when the Thumper Bumper's plunger gets energized
inside its coil..
Edit: I read the above post thinking it was the op (yea I know, not in blue (?))
Anyways, if it is a Thumper Bumper switch, my last reply is worth checking..

Yes, and I might add to check the switches' solder tabs. Perhaps touching or maybe
even a stran of a wire. Also you might want to inspect the plugins for any type of strans
or foreign material. Now and then I had strans that I couldn't even clearly see that caused
hamic, but my first guess would be that the issue is associated at one of the switches that's
in the 10 point circuitry..

Yea, like you say, that switch needs replacing, but because the issue's happening to
all 4 players, I was thinking it wasn't in one individual score reel..

Yup, you need to adjust those switches, but the 10s Score Relay still needs to get initial
juice, so that does point back to the playfield switches. If you haven't already, you might
want to check the playfield plugins on the bottom board making sure no solder splatter,
wire strans, ect. might be making contact with the male and/or female Jones Plugs.
Sometimes switches have such a tiny metalic spec, it's barely visible.
I'd first make sure all the Score Reel switch blades are adjusted proper, then fire up the
machine then pull the playfield plugs from the bottom board (I forgot, but one may also
go to the head), and once pulled, I'm sure the 10s Score Relay will release..

I brought up unplugging the jones plugs because you thought possibly the main issue
may have been in the score reel, but I was pretty certain it being in/under the playfield..
You have schematics, so you have the wire code to the 10 point circuit which should
give you a good idea what wire it is on the jones plug.
If you de-solder that wire from the first switch it goes to on the playfield, the 10 Point
Score Relay I would have to think wouldn't then energize. If somehow it still does, then
there's a problem between that point on the jones plug unless in some flukey way the 10
Score Relay still energizes with the jones plugs unplugged..