Hi HD-Fatboy
here http://mirror2.ipdb.org/files/1072/Williams_1976_Grand_Prix_Manual.pdf on page-12 (ori-10) I can see where the relays and steppers are mounted --- the Left Bonus Relay and the Right Bonus Relay are mounted on the underneathside of the playfield. Lift the playfield - actuate the RIGHT Eject-Hole-Switch - see how the RIGHT Bonus Relay pulls-in ?
Wait till the right bonus is done - THEN try: Manually activate the LEFT Bonus Relay - what happens ? It is late again - till tomorrow, greetings Rolf

Hi HD_Fatboy
an add-on to my post-52: You have lifted the playfield and probably with a finger You have simulated "Ball is in the RIGHT Eject-Hole" - and You have seen the pulling-in of the RIGHT Bonus-Relay.
THEN You do the same on the LEFT - put the finger there so the switch is closed - unfortunately no pulling-in of the left Bonus Relay. Well, we are allowed to cheat a bit - to help a bit --- we can carefully press the armature on the relay (simulate "coil is pulling so the armature is moved") --- so You must use both hands - one hand / finger simulates "Ball is in the Eject-Hole" - keep-on closing the switch --- the other hand / finger / maybe an wooden stick: You press the armature on the relay and let go --- does the relay stays pulling and You have action ? What when You manually press for +/- five seconds ?

About "reading schematics" --- HOW does a ONE-Player-Game steps through the balls in an Williams / Bally (NOT: Gottlieb) FOUR-Player-Pin (?) - want to read the description here: https://pinside.com/pinball/forum/topic/williams-fun-fest-issueshelp#post-4125681 . Greetings Rolf

Hi HD_Fatboy
an important remark - Your (post-53): "Change-Relay is constantly pulling". It is allowed and must for quite a while to "stay pulling" - after a while it should quit pulling and stay for quite a while "non-pulling". Before I dig into the schematics --- the ipdb-manual at page-12 (ori-10) tells me "Number Match Unit is mounted on the Insert in the Backbox" --- it looks like my Space-Mission-Unit - see the first JPG. The second JPG is a copy of a page from here: http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK - make You an link to this site --- VERY helpful stuff. The green arrows in both JPGs are pointing "same direction". When You make 10 points on the playfield: This Unit must step one step --- another 10 points - another step on the unit. DOES the unit step in Your pin when You make some 10 points ? You can carefully press the armature on the unit (wear rubber gloves or use a wooden stick) and then let go - can You step the unit ?
Look at the second JPG - "my letters O and P" --- You have the "my O-type of axis" in Your Unit --- see the first JPG - "my green 3" mounted on the axis sometimes lift a blade "my green 4" so the blade makes contact with "my green 5 blade" --- AND WHEN there is contact: Your Change-Relay pulls constantly --- when there is NO contact: the Change-Relay does not pull. Tell me about the No-Match-Unit in Your pin. Greetings Rolf

0Space-Mission-Match-Unit-real (resized).jpg

0Space-Mission-Match-Unit-drawing (resized).jpg

Check these 3 switches

Pinball (resized).png

Hi HD_Fatboy
a general rule on Pinball-Coils is: The flipperbat-POWER-Coil is allowed to stay pulling for up to one - maybe up to two seconds. After that it may overheat and will get dead - we must buy a new coil.
a general rule on Pinball-Coils is: All other coils on relay and steppers are allowed to stay pilling up to one minute - maybe up to two minutes. After that it may overheat and will get dead - we must buy a new coil.
a general rule on Pinball-Coils is: The Williams-Lock-Relay / Gottlieb-Hold-Relay and Tilt-Hold-Relay / Bally various names-relay: These relays have a special coil - they can stay pulling for hours (((they get hot and the envelopping paper gets brown --- after 20,30,40,50 years of "beeing mounted in a pin": We must buy a replacement coil)))

In post-61 You write: "Game-Over-Relay-LATCH-Coil getrs hot and smokes" - I hope You still can use the coil - BUT: Do not let it stay pulling for more than the 1 to 2 minutes - in Your situation (maybe half destroyed): NOT more then 1 to 5 seconds.
Look at the JPG - the upper part - I showed this part already in (post-30 and) post-42. Maybe You have established Jumper-Wires to this LATCH coil - have forgotten about and by now You have an unwanted "permanent connection" ? Greetings Rolf

0Grand-Prix-pinside-A2-Work (resized).jpg

Hi HD-Fatboy
You must do someting so Your Game-Over-Relay-LATCH-Coil cannot constanty pull - otherwise You end up buying a new coil. One side of the coil has (most likely) two wires "black" soldered-on. The other side has one wire of color-orange-blue soldered-on. Unsolder wire-orange-blue away from the coil - or cut the wire.
When I look at the JPG in here I see "Total Playmeter" and "Coin Unit Reset" and "Game-Over-Relay-LATCH" and "Ball-Count-Unit Reset" and "Player-Unit Reset" --- along "my red / orange marks": A possible way to let the Game-Over-LATCH-Coil constantly fire. Also along "my brown / orange marks" --- so one question is: Does one or more of the mentioned stuff also constantly pull ? The other question is: In the schematics I see "Game-Over-LATCH Coil" is "Z-27-1000" Coil --- in Your pin is it the "Z-27-1000" coil faulty constantly pulling ?

More details in "Theory to come" --- look at the JPG in post-32 - powerside connection --- it is drawn "ready to play" all switches in the top horizontal line are closed - POWER can run to ALL the coils (towards right right right to the flipperbats) - You can play. Your Game-Over-Relay does faulty not move to Game-Over - does therefore not open its switch (in this Power-line-connection) - so You still can move the flipperbats. Greetings Rolf

0Grand-Prix-Work-38 (resized).jpg

Hi HD_Fatboy
hihi - Your post-68 came in --- as I am an great inventor I do post what I was "in progress of writing an post":
All the Interlock-Type-Relays have two coils mounted and the Game-Over-Relay is the Standard-Example to talk about such Interlock-Type-Relays. I made me an mnemonic aid:
"TRIP" (Coil) is a word of four letters
"LATCH" (Coil) is a word of five letters
"Four" is one less then "Five" - therefore on the armature of the TRIP (four letter word) side is monted "One less" then on the armature of the LATCH (five letter word) side:
LATCH armature has mounted an Nylon-Ladder
Trip has mounted (one less means) ZERO Nylon-Ladder.
Greetings Rolf

P.S.: A post to come about "TRIP-Coil constanty pulling"

Hi HD_Fatboy
the "Game-Over-TRIP-Coil" is constantly pulling --- lets look at the lower part of the JPG in post-64. Lets do by now just "troubleshooting" - I encircled "burgundy-red" the coil and also an switch on the relay --- wire-color-black and wire-blue-yellow-white are soldered-on. When the relay is TRIPPED: Switch must be open --- question: In Your pin ? Greetings Rolf

Hi HD-Fatboy
great - You could fix the "Game-Over-Relay" fault.
The "Left Bonus Problem" --- You hav a coil out of the pin - I would like to wait until You have the ordered stuff and have put the coil back into place --- see in post-50, JPG: The Left Bonus Unit should be stepped down by the coil - then my "green wiring" can actuate the Eject Relay.

While waiting for Your replacement stuff to come - lets do some "Theory, reading schematics".
In post-63 You were asking about the "Switch on Lock-Relay and (corrigenda) TRIP-Coil on the Game-Over-Relay". Lets go back in time to the "arcade rooms" in the 1960/70ies --- Saturday Night - many players were playing on many pins. A thunderstorm - and a lightning struck the local power station - a Blackout --- the Operator said "O.K. folks - everybody is going home". The Operator toggled-off all the pins. The next morning (powerstation fixed) the operator walks from pin to pin and toggles-on --- AND HE EXPECTS ALL PINS to be / to switch to GAME-OVER. Some pins were in the midth of a play*** - some has JUST been started - no ball played***) - as the operator toggles-on: The TRIP-Coil on the Game-Over-Relay must fire - the relay must TRIP.

See on the bottom on the JPG in post-64: When we play games and play games --- the "A" makes the game end - making the relay to TRIP.
At these times - people with a lot of money may have played just one ball - then said "What a lousy first ball - I / we do not want to play the rest of the balls - I / we start a NEW game" - so the starting makes the "B" pull-in - either the "C" or the "D" is closed (a ball has been played so either there was stepping on the ball (ONE-Player-Game) or then stepping on the Player-Unit (2,3,4 player game) - the Game-Over-Relay is TRIPPED for to start a new game.
And the "E" is for the "Thunderstorm and a lightning" situation: I do not really like the solution the manufacturer made - the switch "E" is adjusted "opening very LATE" when the Lock-Relay pulls-in --- a short period of time (Lock-Relay starting to pull-in): Current is flowing, Switch "E" is still closed - THE Game-Over-TRIP-Coil is made to pull-in. Yes, this works - but the Switch "E" must be adjusted " to open LATE when the armature is moved.

Maybe You have read the above and say: (Thunderstorm situation) Midth of a game*** then the Switch "C" or "D" are closed - the starting a new game by the player makes the Game-Over-Relay to TRIP - Yes - but the toggling-on by the operator would make the pin resume on the situation "the day before - pin in play".
Maybe You have read the above and say: (Thunderstorm situation) No ball played***: At the time the blackout occured - Player-1 was PLAYING ball-1 - he has made points - but ball was still in play (when the blackout occured) - there was no stepping on the ball. Greetings Rolf

Hi HD_Fatboy
I know nothing about shuffle bowlers. Write if You have other problems in Your pin - write when You got the replacement stuff. Greetings Rolf