Well, this is fun; the schematic is all chopped up, but you can find it and the manual here: http://mirror2.ipdb.org/files/2352/Williams_1974_Star_Pool_Maunal_Supplement_Schematic_Diagrams.pdf

Check the NO sw. 'D' (last one away from coil) on the Lock relay, the Game Over relay, and the wiper finger on the Ball Count unit for cleanliness and contact.

Hi Lambecka
I refer to https://pinside.com/pinball/forum/topic/williams-star-pool-ball-count-advances-to-end-game#post-3894140 --- make an "righthandside mouseclick on the schematics / PDF - then choose "save target as" - make Yourself an copy on Your computer - and You can look at it.
Of course - what I wrote in the last paragraph in the pinside-post is still valid. Greetings Rolf

The reset cycle/start up is on p. 2 of the manual.

Hi Lambecka
good - You have an paper schematics. Lets look at the problem "starting a new game - the ball should be kicked out" --- read this https://pinside.com/pinball/forum/topic/williams-star-pool-ball-count-advances-to-end-game#post-3904121 . In Your post-2 You mention "Outhole-Relay pulls in (((but does not stay pulling for a while))) --- so the "my encircled LEMON GREEN" Self-Hold-Circuitry does not work. The ipdb-manual on page-23 (ori-21) shows on Outhole-Relay: Bottom-most switch - Switch "A" is the Self-Hold-Switch - check this switch. The schematics says "three-bladed Make-and-Brake-Switch Motor-5B" is to check. The schematics tells us: Real motor - then INDEX-Cam - then cam-1 - then cam-2 - then cam-2-long-dwell - then cam-3 - then cam-4 - then cam-5 --- the two topmost-blades to inspect. Greetings Rolf

Hi Lambecka
good - some progress. Here https://pinside.com/pinball/forum/topic/williams-star-pool-ball-count-advances-to-end-game#post-3904121 I wrote about the "not loved by me feature 'every ball given comes as ONE-Bonus given' " --- so when the very first ball is kicked over to the shooter alley: DOES the bonus-ladder on the playfield then shows "1 bonus" on the ladder ?

The mystery of "50 points given" maybe a friend helps - one of You makes the pin to start - the other one stares at the 50-Pint-Relay - does the 50-Point-Relay pull-in and stay pulling for a turn of 180 degrees of the motor (((this fault by now is an mystery to me))) ? Greetings Rolf

Hi Lambecka
the following text I have written not knowing Your post-10. I will look at "Spinner-Relay" by tomorrow.
Hi Lambecka
when You look at the schematics at "A-15 / A-16" You see the drawing of the Score-Motor-INDEX-Cam - Switch "D" is an three-blades Switch --- the topmost two blades have the text "MOTOR RUN". Once the pins is started and the first ball is kicked-out to the shooter-alley - and the pin idles - sits there doing nothing - You take an wooden stick or You wear rubber gloves - YOU gently press downwards in the pin - gently press down the topmost-blade and then let go --- the motor should make a turn of 180 degrees, then stop. Within that turn of 180 degrees NOTHING else is allowed to happen --- question: Do You get faulty 50 points on the Score-Drums ?

It has been a busy day - I go to sleep, till tomorrow, greetings Rolf

Hi Lambecka
please do the test I mentioned in post-11 --- I am chasing the "starting for second player adds 50 points to Player-1-Score-Drums" --- starting for second player makes the motor to turn 180 degrees --- so what happens when You (the test) make the motor to turn 180 degrees ? Greetings Rolf

Hi Lambecka
good - You studied the "pin and/or schematics (?)" and have found Score-Motor-Impulse-C (Switch).
A fact to Score-Motor-Switches: Whenever the motor turns for 180 degrees: ALL / EVERY Score-Motor-Switch(es) are actuated - ALWAYS / ON EVERY TURN. Whenever an specific feature needs the help of the motor (to make a turn (of 180 degrees)): The specific feature closes its specific-feature-switch to ALLOW current to pass - current that motor-switch(es) deliver. When another feature calls for help: The "another feature closes its 'another feature-switch' to allow current to pass".

See the JPG - along "my green lines" is the feeding /toc toc toc toc toc of the 10-Point-Relay: Score-Motor-IMPULSE-C does close five times in a motor-turn. I have encircled red the "feature-Switch" - the "Switch on the 50-Points-Relay to let the needed five pulses through".
Please do the test of post-11 again - make the motor to do a turn (of 180 degrees) - watch the 50-Points-Relay --- IF (if, if) the 50-Points-Relay DOES pull-in and stay pulling: We must look for "WHY DOES the 50-Points-Relay faulty pulls-in ?".
IF (if, if) the 50-Points-Relay does NOT pull-in: Please inspect the "encircled red" switch --- faulty closed when the relay is not pulling ? a drop of solder fallen at the solder-lugs on the switch-blades - making faulty connection ? - a doghair crap of wire fallen there making faulty connection ? Greetings Rolf

0Star-Pool-Work-05 (resized).jpg

Hi Lambecka
I try to have the test as simple as possible - thats why I was / am asking "doing the test as described in post-11". When doing this test: NO FEATURE is calling for help of a turn of the Score-Motor --- NOTHING (besides the motor turning) is allowed to happen . When You start a game then "starting a game needs help of the Score-Motor --- some stuff then does happen".
I just want the motor to do a turn - thats all.

You already had said and in post-15 You say it again: The SPINNER-Relay does actuate.

See the JPG in post-14, just above the horizontal green line: See the "Switch on Advanced Spinner-Relay" with wire-color-grey-white and wire-color-red-black(third place used). Does the relay (faulty) pull-in ? IF (if, if) the Advanced-Spinner-Relay does NOT pull-in: Please inspect the "switch on the relay" --- faulty closed when the relay is not pulling ? a drop of solder fallen at the solder-lugs on the switch-blades - making faulty connection ? - a doghair crap of wire fallen there making faulty connection ? Greetings Rolf
P.S.: I would like to stick to this (first) fault - otherwise my posts get way to long.

Hi Lambecka
I am running out of ideas - I repeat - DOES the Advance-Spinner-Relay (faulty) pull-in when You simply make the motor to do a turn ?
in the ipdb-manual http://mirror2.ipdb.org/files/2352/Williams_1974_Star_Pool_Maunal_Supplement_Schematic_Diagrams.pdf - on the bottom of page-27 (ori-25) - the switch B is in question - have a very good look at.
Maybe we (means You) must unsolder wire-red-black away from the switchblade - then do another test.
IF (if, if) the fault still shows up (Spinner Relay rhythmically pulling in): On other locations (we see in the schematics) You must unsolder another wire-red-black - another - another --- until the fault no longer shows up means the faulty wiring has been found.

(((If I must unsolder a wire away somewhere - BUT I do not have good access to the solder-lug: I am rude and take an old scissors and cut the wire about two inches means 5 cm away from the solder-lug --- later twist the cut ends and put some solder on to reconnect)))
Greetings Rolf

Hi Lambecka
Advance-Relay pulling every second turn: not pleasing - another problem.

Lets think of a fully running pin having a "green-Lamp-Relay". This "green-Lamp-Relay" has an Normally-Open-Switch --- when the relay is pulling then the switch is closed and so the green lamp on the playfield is lit. When the relay is not pulling then the switch is open and the green lamp on the playfield is not lit.

But now we have an fault - the fault "green lamp is always lit". TWO ways / possibilities of "fault" - first way is: The relay faulty pulls - the switch therefore is entitled to be closed - the green lamp is lit. Second way: The relay is nice and does not pull - BUT the switch-blades are bent - making contact even when the switch should be open - or a drop of solder making faulty connection or a doghair of wire making faulty connection.

Back to the Advance-Spinner-Relay and switch - You say: 100% sure it is not "first way" - but how about "second way" - blades bent, solder-drop, doghair crap of wire ? Greetings Rolf

Hi Lambecka
I am tired and frustrated (or frustrated and tired) - I go to sleep. Till tomorrow, greetings Rolf

Hi Albert
great - You have found the fault.
(((I wonder how pilots and flight attendants can live a "normal" Life beeing all the times in different time zones. The switching to daylight saving times comes soon - I try to make it easyer to me --- four weeks in advance: Every week I get up 15 minutes earlyer. I am tired / uneasy all day long ...)))

I do have an meter but I usually do not use it because there are many wirings and we may get a "false reading" because we kind of measure "all the way around through the windings of the transformer". If its easy to do: Please measure again at the switch and tell me: Does Your meter by now shows NO CONNECTION ? I then can take "using a meter" into my "advising for troubleshooting".

Do You still have the problem: The first ball made some points and 2,3,4 bonus - You loose the ball --- ball lays in the Outhole and now the motor turns and turns and turns ? OR: Nothing happens ? Try: Then press the armature on "Bonus-Relay" - do You get action ? Greetings Rolf