Hi futurepinhead
I take "3." in Your post-1 --- when You toggle-on the pin the first time in the morning - does the Lock-Relay pulls-in and stays pulling ? After some games You toggle-off the pin - does the Lock-Relay let go / quits pulling ? Did You or some previous owner manipulate the Lock-Relay - to have it (mechanically blocked) ALWAYS IN POSITION "PULLING" ? Greetings Rolf

Hi futurepinhead
in "2." in Your post-1 You kind of write "can start a ONE-Player-Game". You start a One-Player-Game - You play Ball-1, loose Ball-1 - the pin steps to Ball-2 and NOW: What happens when You press the Credit-Button / Start-Button ? Does the pin starts a new game means "Score-Drums in the Backbox do reset and the pin resets 'Ball in Play (Backbox)' to 1 " ?
(See here https://www.ipdb.org/showpic.pl?id=438&picno=44263&zoom=1 - Ball in Play is 1 --- do not look at the "Over the Top") Greetings Rolf

Hi futurepinhead
look at my JPG - I believe "my green wiring" works. You have played ball-1 - the pin steps to ball-2 - this means the switch on the Ball-Count-Unit (my green "1") is no longer open - You press the Start-Button - this makes the Coin-Relay to pull-in, so switch "my green '2' " closes and so the Game-Over-Relay (my green 3) trips.

I believe "my orange wiring" does not work. Bally pins are DANGEROUS - the coils are operated by 110 VAC and 48 VAC - such voltage can kill You --- toggle off the pin and unplug the main power cord - then look at the switches on the (of course non-pulling) Lock-Relay - do You see a Normally-Closed Switch on the Lock-Relay having soldered-on "Wire-Yellow" and "Wire-Green-Red" ? (((You can see wire-green-red for reference, color on the Adj-Plug-Wire "3-5 balls))).
Please - do not yet do a test - simply (pin toggled-off, main power cord unplugged) look out for this switch on the Lock-Relay - wires truely soldered-on ? - contact-points on the switchblades clean ? switch truely closed when relay is non-pulling ? Greetings Rolf
P.S.: In Switzerland it is getting late in the evening (hour 22:30) - this might be my last post for today.

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Hi futurepinhead
first I stay with the JPG in post-6. When current does not flow when the current should flow it is either the relay non-pulling so switch is open - OR the switch is no good OR in the wiring is the fault. Please practice having the pin toggled-off and the main power cord unplugged: Wear rubber gloves, use an screwdriver with "electrical insulated handle" - try, do hold the tip of the screwdriver at the two blades of the switch on the Lock-Relay - try several times - the tip of the screwdriver shall touch both blades AND the tip of the screwdriver ONLY touches these two blades - in other words "With the tip of the screwdriver You make connection through the switch".
After practice comes real test --- plug-in, toggle- on, start a game - the Game-Over-Relay is latched (is in play), the Lock-Relay is pulling and so the switch is open, NOW (wear rubber gloves and) use the tip of the screwdriver - touch the two blades - big question: Does the Game-Over-Relay trip (comes to Game-Over) ? If Your answer is "No" then the fault is in the wiring.

Second - to the JPG in here - it is about "Why can You not start for a second player" --- in post-1 You wrote "hit the Start-Button - it doesn't matter - it only plays a One Player Game".
Question: After You have started a ONE-Player-Game You press the Credit-Button - DOES the Credit-Unit subtracts a game (does the Credit-Unit step down one step) , does the Credit-Relay actuates, does the Score-Motor turns half a revolution ?
If Your answer is "Yes": See the JPG here - "encircled brown" area is of interest.
If Your answer is "No": "encircled blue" area on the left of the JPG is of interest - actually the "drawn closed Switch (Limit) on the Coin-Unit" - this switch must be closed "1- or 2- or 3-Player-Game" - this switch is allowed, must be open "4-Player-Game".
(((The manufacturer put this switch in the pin "once a FOUR-Player-Game has been started : erronous / mistaken pressing the Credit-Button shall not subtract a game from the Credit-Unit - as it is not possible to play a 5-Player-Game on a 4-Player-Pin ...))) Greetings Rolf

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Hi futurepinhead
may I read from Your post-10 and post-11 "can start a 1-, 2-, 3-, 4-Player-Game" ?

Great - You report in post-9 "testing with the tip of a screwdriver --- and the Game-Over-Relay trips". The test was for "is there continuity through all the connecting wires ?" - and Yes there is continuity so we get to the next questions "is the switch (contact-points) on the Lock-Relay good ?" and "is the switch (moved blade) adjusted correct ?". I use a rough cardbord or very-fine sandpaper to clean the surface of a contact-point mounted on a switchblade.
The switch on the Lock-Relay (You did the test with the tip of a screwdriver) is a very special switch - it is a Normally-Closed-Switch AND MUST be adjusted to open late, very late. Toggle-off the pin, unplug the main power cord - with a finger press the armature on the Lock-Relay and watch the switchblades of the switch --- as You slowly, constantly press the armature You should see: The "nylon-ladder mounted on the armature" moves one blade of the switch --- AND THE OTHER BLADE (of the switch) follows, has still contact with the one, moved blade. And then almost to the end of travel / Your moving the armature: The switch opens as the one, moved blade moves a bit further. Please check this moving of the blades.

Theory - You toggle-on the pin - current starts flowing to the Coil on the Lock-Relay (to make the Lock-Relay to pull in) --- and at the same time current starts flowing to the Trip-Coil on the Game-Over-Relay (to trip the Game-Over-Relay (((if it was not tripped at the time You toggled-off))) ).
In the wiring to the Trip-Coil on the Game-Over-Relay is a SWITCH on the Lock-Relay - opening, cutting current to the Trip-Coil on Game-Over-Relay. We want to help the Trip-Coil - we adjust the SWITCH on the Lock-Relay to open LATE, very late (((BUT the switch MUST open))).

In another topic I was writing about "self cleaning" of switches - I there wrote about the "50 percent rule", unfortunately I there did not write about Lock-Relay-SWITCH --- the Lock-Relay-SWITCH should be adjusted "about 80 percent of travel the two blades shall have contact - then finally the SWITCH opens". May want to read this: https://pinside.com/pinball/forum/topic/1965-bowl-a-strike-crazy-at-startup#post-3231326

Thanks for the video (post-11) - by now I do not have an explanation to the phenomena - I hope "your checking / adjusting (open late) the SWITCH" makes the pin to act normal. Greetings Rolf