I would make sure the micro switch on the button is actually being depressed. Also test the switch itself to make sure it has not gone bad.

Reseat all of the Jones plus (inteconnectors) in your machine.

Hi pinbrick
I refer to: https://pinside.com/pinball/forum/topic/bally-game-over-interlock-relay-wont-pull-in-when-starting-game#post-3065127 - I don't want to post the same JPG in here. Do NOT read the "text THERE" - I will write here and make references "JPG-there".

You want to start a new game - You press the "Credit-Button" --- see JPG-there, "orange stuff", many switches that can be faulty.
I would like to narrow-down on the problem. Once the pin gets to "now lets start and do reset": COIN-RELAY pulls-in ---
Please try: Push onto the "armature / anchor-plate" on COIN-Relay --- what happens ? (The pin should start a new game. Greetings Rolf

Hi pinbrick
see JPG-there - marked "light-blue": You manipulated the Coin-Relay to be "pulled-in" - Switch on Coin-Relay is closed and so the Score-Motor makes a turn.

To the right of this - more marked light-blue: The Score-Reels have some points*** on the Reels - one or more of the 16 switches is / are closed, Switch on Game-Over-Relay*** is closed, Reset-Relay will be activated and establishes "Self-Hold-Current through "marked dark-blue".
This does not work in Your pin, so try: Push onto the "armature / anchor plate" of Reset-Relay. Does the pin start the game / reset ?

The Score-Reels have some points***: A fully functioning pin DOES start a new game with ALL 16 Score-Reels beeing at Zero-Position --- when troubleshooting I like to have some points on the Score-Reels to clearly see and hear: The pin does reset. So I suggest: ALWAYS put some points on "one or two of the Score-Reels of player-1".

Switch on Game-Over-Relay***: The schema is drawn in a specific state*** - during start-up / playing many of the switches are moved - and moved back - maybe moved again and on and on --- we must think into the schema "where are we now in the lifetime of a game" - is this and this switch at the very moment "open or closed". When we start a game: Switch on Game-Over-Relay*** is closed.

Schema drawn in a specific state*** - on "Bally / Gottlieb / Williams pins": A game for ONE player has been started, reset is done, ball is kicked over to the Shooter-Alley ready to play (ball is not launched, no points are made), Line-Cord is UNPLUGGED - NO CURRENT in the pin, so simple relays do not pull. BUT
during a reset: Game-Over-Relay is moved - it is "latched / untripped" --- and unplugging the Line Chord has no effect on the Game-Over-Relay - it stays latched (ready to play).
WE WANT to start a game - WE WANT the Game-Over-Relay tripped and so Switch on Game-Over-Relay*** closed.

Want to try ?: Do Your tests twice - one time the Game-Over-Relay in state "A, tripped" - then the same test(s) with the relay beeing in state "B, latched" - You simply fumble / press on the anchor-plates before You do the same test ...
Greetings Rolf

Broken relay - reset scores 3 and 4.
Reset contacts on scoremotor have a to great gap and not making contact?
Contacts are on one of the 5 step discs on the scoremotor.