Backstory time.
Recently shopped out a Gottlieb Playball. Everything game wise is working fine now, and it's set to free play.
I can't leave well enough alone though, and so even though it's on free play, I'd like the coin mechs to operate correctly.

To my knowledge, Playball was originally intended to have three coin chutes. This bit from the manual seems to agree.
IMG_3672 (resized).JPG

My machine though only has two chutes. Additionally - there are no AS "2 coins per play relay" or X "2 play relay" relays as mentioned above. No cut wires or anything - it's just like they were never installed.
IMG_3673 (resized).JPG
And my W relay is labeled "Additional Chute Relay" instead of "3rd Chute Relay"
IMG_3675 (resized).JPG

My adjustment plugs also differ a bit from the manual's description.
IMG_3662 (resized).JPG

I thought for sure that I was just missing things, but compare an IPDB photo to my own.
image-12 (resized).jpg
Fewer adjustment plugs, and two missing relays.
IMG_3676 (resized).JPG

I'm assuming I have a later version of the game where the 3rd chute was done away with?

Regardless the reason - here's the issue.

The game is on free play, but I need something to putz with, and since it came with two 25 cent coin mechs, I'd like those to add the usual(?) two credits per coin.

The adjustment plugs seem pretty simple. First (left) chute is controlled by the "1st coin chute adjustment" plug.
Leaving it unconnected gets you nothing with the left chute.
Plugging it into the first "1 play" plug starts a game on coin drop. Subsequent coins just start the game over.
If I'm understanding it right, if you plug it into the second plug, a coin drop should get you the number of credits determined by the second plug.

However, I'm getting double the credits expected.
A breakdown of the credits given. 1st chute plug in second position for all.
Extra chute plug not connected - 4 credits.
ECP in 2 play position - 4 credits.
ECP in 3 play position - 6 credits.
ECP in 4 play position - 8 credits.
ECP in 5 play position - 10 credits.

For what it's worth - if you put a coin in the 2nd (right) chute, you get the same behavior.
Extra chute plug not connected - 4 credits.
ECP in 2 play position - 4 credits.
ECP in 3 play position - 6 credits.
ECP in 4 play position - 8 credits.
ECP in 5 play position - 10 credits.

Side note : dropping an additional coin when a game is running will restart the game, and add 3 credits. (Or 5, 7, 9)

So what's going on? When the game adds four credits, I can hear the relay + coil fire just two times, and the credit wheel distinctly jumps +2 twice. Yet if I manually manipulate the coil - it only increments the wheel 1 credit. And as mentioned right above - if you drop a coin while a game is being played - it restarts the game and adds three credits, 2 at first, then another.

In case it makes a difference - my door wire harness seems hacked up. It's a 10 prong jones plug with wires on 9 of the prongs.
IMG_3666 (resized).JPG
Lots of bits of electrical tape where I assume things were cut and reconnected.
IMG_3667 (resized).JPG

Any ideas on where to start or what to do?

Edit - checked under those bits of electrical tape - it's not really splices, just covering areas of bare wire.

Also traced all of the wires from the jones plug if needed.

Running clockwise-ish from the empty prong (Colors might be wrong - it's hard to tell.):

The black-yellow and black-white wires run to the coin door lights.
The solid black wire runs to one tab of the lock out coil.
The brown-green (I think) wire runs to the slam tilt switch.
The blue wire runs to the coin switch on the left side.
The orange wire runs to the coin switch left side -> lock out coil -> start button -> coin switch right side.
(It may run to the lock out coil first and then through the left coin switch, not sure on the order.)
The maroon/brown? wire runs to the slam tilt switch.
The green wire runs to the right coin switch.
The white wire runs to the start button.

Can post close ups of the schematics for the replay+ coil and coin switches if that would help. Though the schematic is referencing the AS and X relays that dont appear to exist in my machine.

edit - wondering if the coin switch isn't bouncing and registering two hits for each coin. I knew I should have just put it on free play and never looked back.

Thanks Rolf. Interesting about the optional coin chutes. I assume operators were able to specify what they wanted when ordering.
Found another picture from a Playball restoration showing even fewer adjustment plugs. Two coin chutes, but only one adjustment.
PB_Bottom_Board1_After (resized).jpg
I assume this would be a case of quarters only, with the single plug determining credits per coin.

I think I'm gonna play with it a bit longer and see if I can figure it out. Just bugs me that it's 4 credits per coin. That seems nuts.
If not, I'll just put in two new "25 cent 2 play" entrance plates on it and call it a day.

Edit - well it's clearly not the coin switch bouncing. Not going to worry about this.

Unless someone reads this and off the top of their head knows why it would do this - whatever. If I really wanted to get it done I could wire the coin switches directly to the replay add coil I suppose. Would also fire off the knocker I think.