Hi Matt
Your description is not so good.
I show a 1-player-game, first ball is in play -> You make some points -> Ball-Index-Relay pulls and keeps-on pulling (does it in Your pin ?) -> You make some bonus -> You loose the ball -> ball rolls into the Outhole -> Bonus is counted down (does it in Your pin ?) -> (Alpha) the Outhole-Relay pulls and stay pulling for a while (does it in Your pin ?) -> Score-Motor starts and makes a turn (does it in Your pin ?) -> Ball-Count-Unit-Step-up Coil fires (Your pin: Sometimes) -> One Bonus is put on the Bonus-Ladder (does it in Your pin ?) -> ball is kicked-over to the Shooter-Alley (does it in Your pin ?).

In Your snippet of schema I show starting with "Alpha" -> green lines -> through many closed switches the Ball-Count-Unit-Step-up Coil is activated -> encircled-green -> Player-Reset-RELAY pulls and keeps-on pulling for a while. Through orange-lines (the Score-Motor is still turning) NOW the "Player(up)-Unit-RESET-Coil fires (not needed in a 1-player-game --- but this is done).
Then (not on the snippet): The turning score-Motor closes a switch -> through closed Switch on pulling Outhole-Relay -> one bonus is added and the ball is kicked-over to the Shooter-Alley.

Matt, WHERE in my description (through the steps) does Your fault show-up ?

Whenever I read "Sometimes it does - sometimes it doesn't": I assume "somewhere a wire has broken-off a solder-lug - wires are stiff, (broken-off) they stay in place - a bit of shaking / vibration -> wire moves a bit -> no connection -> -> -> shaking / vibration -> wire moves back -> connection again ... WHENEVER I LOOK AT A SWITCH / SOLDER-POINT: I do not only look at BUT I grab every wire and gently pull a bit -> Is the wire REALLY soldered-on.

IF (if) Your problem is (Outhole-Relay pulls / Score-Motor runs): I would FIRST check all solder-pionts and wires soldered-on --- taking the snippet of schema - following the green-line(s) - every switch with its wires. Greetings Rolf

zFlip-Flop-Work-01_(resized).jpg

Hi Matt
I - Rolf DO NOT LIKE working on Score-Motor-Switches - I do quite many tests -> ONLY when I am 100% sure "THIS SCORE-MOTOR-SWITCH IS BENT AND MUST BE ADJUSTED": THEN I work on that Switch. Other people may / do think different ...

So I would use Jumper-Wires (my "many tests" (((to make sure ...))) ).
In a 1-player-game the connection "Score-Motor-3A-side--wire-grey-red <-> Coil on Ball-Count-Unit-Step-up---side-wire-orange-white": This connection is "ALL THE TIME (((because ONLY ONE player plays))). I would establish a permanent Jumpering - "my light-blue line".
Maybe it is impossible to clip-on the Jumper-Wire at the "Solder-Lug SCM-3A-side-grey-red" (not enough room) -> so I would establish my "middle light,middle dark blue" permanent Jumper - clip-on at the "Coin-Unit-wire-grey-red". (((And I keep in mind: "The wire-grey-red is in my circuitry - if wire-grey-red itself is broken -> faults))).

If You want to look at SCM-3A -> let a friend help You. You establish two Jumper-Wires and take the other ends into the open. Your friend does handle the pin (imitating ball play / loosing ball (he places his finger in the Outhole and get kicked by the Kicker) - YOU have the two ends of these Jumper-Wires in Your hands -> at the time the Score-Motor turns -> You make a "grace shot" - holding the ends together for a short time - then let go - YOU ARE PART OF THE BRAIN OF THE PIN -> YOU do close SCM-3A at the right time.

Look at the schema and think "where can I set Jumper-Wires" - "what do I test with this setting" - "what does the result tells me" ... another specific test depending on the answer of "test-before". Greetings Rolf

P.S.: I said it in the beginning of this post - I say it again: I, Rolf, I do not like to work / testing on Score-Motor-Switches - other people very well "can / do have" another opinion.

zFlip-Flop-Work-02_(resized).jpg

I had this issue on my bally. It ended up being a broken solder joint on the score motor switch stack. They used large gauge wire as a bus between multiple contacts on the stack and the bottom one was broken. I noticed your switch in question is also on the bottom...

https://pinside.com/pinball/forum/topic/bally-bow-and-arrow-ball-count-advancing-intermittently#post-2980072

Hi Matt
I have a vague theory. The topic is old - I kind of start at the beginning and ask: You play a ONE-Player-Game - You loose Ball-1 - does the Outhole-Relay pull-in, Ball-Index-Relay is pulling, Score-Motor turns, NO FIRING of Ball-Count-Unit-Step-UP, Player-Reset-Relay, Player-Up-Unit-Reset, Player-Up-Unit-Step-Up ? (((These words recall the JPG in post-4, green and orange-brown)))

The vague theory (my red star in JPG here) the Score-Motor-Switch-1F is faulty ALWAYS closed. And so the Outhole-Relay sometimes (odd numbers of bonus) gets activated too early compared with "even numbers do activate it at a good time".

Do not spend hours - the theory is vague, crummy --- do several times "even numbers" and look at the Score-Motor turning the bakelite wheels - also look at the Outhole-Relay pulling-in. I believe "even numbers" make the Outhole-Relay pull-in WHEN the Score-Motor is in HOME-Position (am I right ?).
Then do the faulty "odd numbers" - question: DOES the Outhole-Relay pull-in at "Score-Motor is in ANOTHER position" ?
IF (if) "ANOTHER position": Want to look at Score-Motor-Switch-1-F - does it TRUELY opens ?

I read the schematics (my JPG) as: "light-green" - "dark-green" - "light-blue" - "dark-blue".
The "Bonus-ZERO-Relay" pulls-in when the Bonus is counted down --- so Switch (my dark-blue star) is immediately thrown - BUT with an functioning SCM-1F (my red star): The Score-Motor must turn further - reaching "Home-Position" - THEN the Outhole-Relay shall pull-in.

Again - my theory is vague, crummy - do not spend hours - important is the answer to the question: Outhole-Relay pulls-in at Score-Motor-Position-XYZ. IS XYZ always "Home-Position of the Score-Motor" ? Greetings Rolf

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Hi Matt
I believe there is a fault in the drawing "schematics" - in the JPG, post-7, on top, encircled dark-green, Switch on Bonus-Zero-Relay: I want this switch to be an "Normally-Closed-Switch" - so in the schematics the switch should be drawn with a dash through the switch.

An EASY way of testing my theory: Do NOT let the BALL roll-in into the Outhole. SIMULATE with Your finger: You put Your finger there - CLOSING the Outhole-Switch. AS SOON as the Bonus-Ladder starts stepping down: TAKE AWAY the finger - so the Outhole-Switch OPENS (a faulty-always-closed SCM-1F cannot harm - as the Outhole-Switch is OPEN).
WAIT until the Bonus-Ladder is stepped completely down and the Score-Motor has reached Zero-Position - THEN close the Outhole-Switch again with Your finger - THEN the Outhole-Relay is allowed to pull-in. Greetings Rolf

Hi Matt
the theory is: "Switch-SCM-1F" is faulty-always-closed so the Outhole-Relay does pull-in at a "not correct time". The EASY way of testing takes advantage of the fact "when using a finger we can OPEN temporary "another switch in the circuitry" - I would like to read about the result of "EASY test", greetings Rolf