First check the switch blades/contacts on that relay are clean and properly adjusted. Do this with the machine power cord unplugged from the wall outlet.

If those check out ok, then the lock relay coil is probably bad (gone open circuit) and should be replaced with a brand new coil.

Hi Mark
DANGER --- Your pin is an rather old one and has a lot of stuff operated by 110VAC. You do not want to get killed --- so ALWAYS unplug the 110VAC main power cord: When "working in the pin" --- when "just looking". ONLY plug-in when You NEED current for a test.
See JPG-1 (an old one - I happened to use "chasing fuse blowing") - only look at "RED" wiring: ALL RED WIRING is permanently connected to 110VAC-POWER when You do have the cord plugged-in --- DANGER.

Troubleshooting in Your pin: See the top of second JPG - the Game-Over-Relay (the drawing is actually "Bally-Game-Over-Relay") --- UNPLUG the main power cord and look at Your Game-Over-Relay --- it MUST be tripped - You may have to trip it manually. Then plug-in and try the Left Flipper-Button.

No Luck means The Lock-Relay does not pull-in ? --- The "green stuff" shoes the "Kickoff-Switch" - maybe faulty. UNPLUG the main power cord and establish a permanent Jumper "my yellow stuff" - see the yellow dot on the transformer - having soldered-on two wires "yellow". Then plug-in and try.

Still no luck --- UNPLUG the main power cord and establish one more jumpering - my "RED" --- PLEASE DO USE "side on 15 Amp Fuse where wire-BLACK is soldered-on" --- as we want the fuse in our wiring. So by now You have a permanent jumper "yellow" and You have a permanent jumper "RED". Then plug-in and try.

- No reaction at all means Coil on Kock-Relay is dead.
- Fuse blows means the coil is shot making a short.
- Lock-Relay pulls-in and stays pulling means we must look at wiring and switch on Game-Over-Relay.
- Other reaction (?), hmm
Greetings Rolf

P.S.: See in the first JPG - "encircled orange": As long as You press the left flipper-button: As long YOU feed 110VAC to transformer.

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Hi Mark
great - progress.
Now the machine resets - but the ball is not kicked out and the motor runs forever. We usually say "A fault on the Score-Drums" - they do NOT "report to the 'brain of the pin': We Score-Drums are resetted" - so the pin tries and tries to reset to get the report from the Score-Drums.
BUT also: OTHER faults can let the Motor run forever.

I ask questions - then I will come up with snippets of the schematics. Look at the first JPG in post-3 --- the Replay-Relay and the Coin-Relay - questions: Do You start a new game by throwing-in a coin --- or do You press the button on the cabinet (Credit-Button / Replay-Button, Start-Button).
The Coin-Relay and maybe the Replay-Relay pull-in at start-up --- question: Do they "let go after a short period of time ? (they should).

Before starting a new game: The Game-Over-Relay MUST be tripped (You may have to do it manually). THEN start a new game - look at the Game-Over-Relay - question: Does it MOVE means does it LATCH ?
Look at the Reset-Relay (when You start a game) --- it must pull-in, stay pulling for a while --- then let go - question: Does the Reset-Relay LET GO after some time (chances are: Reset-Relay does NOT let go).
Please write about "observations" so we can narrow down on the fault, greetings Rolf

P.S.: I REPEAT my warning: DANGER --- 110VAC all around in the pin --- NEVER "work" when the pin is plugged-in - or You can get killed.

Hi Mark
grumble - me writing on a post (to come) - AND You write a post ...

Well, here is my post - not knowing about Your posts -13 , -14, see the P.S. at the end:
Hi Mark
the "problem" in reading schematics is: The schematics is static - a momentary snapshot - but through resetting and through playing: The Score-Motor runs (sometimes) - relays actuate - switches close and open - steppers step --- WE must think the factor TIME into the schematics - it would be nice to have an animated schematics --- AND SteveFury MADE such an animation of the Start / Reset of Space Mission (copy that link, link to SteveFury-video): https://pinside.com/pinball/forum/topic/em-pinball-circuits-basics-to-not-so-basic/page/3#post-3587920 /

The Space Mission is an late EM-pin - maybe 5 to 10% in the video is NOT in Your A-Go-Go.

Look at my JPG - the Coin-Relay is made to pull-in --- then "light-green": A LOT is resetted. The "encircled orange" Switch on Game-Over-Relay is CLOSED when the relay is tripped (((BECAUSE of THIS switch we must trip the Game-Over-Relay before starting a new game))) - so the Reset-Relay is activated. THEN "dark-green": "Self-Hold-Current of the Reset-Relay" is etablished and the 16 Score-Drums are resetted. We fear: One of the switches on the Score-Drums is faulty - NOT opening so this makes the Reset-Relay STAY pulling and so making the Score-Motor run endlessly. (((See on top of the JPG: The switches they make the Score-Motor run)))

RELIEVE - thanks for the videos - The Reset-Relay LET GO. So we look again at the top of my JPG - the OUTHOLE-RELAY --- question: Does it pull-in and STAYS pulling ? Greetings Rolf

P.S.: The OUTHOLE-RELAY is of interest - Does it pull-in and never let go ?

Hi --- today it is strange with "uploading JPGs, greetings Rolf

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From the schematic we see that the outhole relay is energized via the outhole switch, through a normally closed switch on the eject relay and a make/break switch on the score motor impulse cam (double-check the score motor diagram, a bit hard to see the schematic).

Check all of those switches along the circuit for correct gap and continuity.

Hi Mark
hmm, by now You have two faults - first: WHAT makes the Score-Motor turn forever ?, second: WHY does the Outhole-Relay NOT pull-in ? For a while I would like to stick to second problem.

Your snippet of schematics (post-17) shows: EITHER the ball is laying in the Outhole between the flipper bats - OR YOU manually close the Switch there. Look at the underneath-side of the playfield - DOES this switch CLOSE when activated ? DO CLOSE this switch.

You close that switch but the Outhole-Relay does not pull-in (?) The Score-Motor is involved with its switch SCM-Index-Wheel-Switch-C --- so keep the Outhole-Switch closed for 2 to 3 Score-Motor turns.

STILL - the Outhole-Relay does not pull-in (?). As many relays the Outhole-Relay has its "Self-Hold-Switch" - lets try this "Self-Hold-Switch / Self-Hold-Circuitry". In the "Self-Hold-Circuitry" the Score-Motor-Switch "6-A" is involved. Look in Your schematics at the drawing of the Score-Motor-Wheels - and look in Your pin - find Score-Motor-Wheel named "6", see how the switch SCM-6A actuates rarely (acuates once for a short time each turn - means actuates two times per FULL revolution).
Look at Your Outhole-Relay - at time "SCM-6A does NOT actuate": Press the armature of the Outhole-Relay and let go on the armature - question: Does the Outhole-Relay STAYS pulling until the Score-Motor actuates SCM-6A ?

Maybe we are lucky - Look at the Eject-RELAY - probably mounted on the underneathside of the playfield - is it nasty - is it PULLING all the time ?

I am guessing and I make You do some work - a relay can be faulty pulling (easy to be seen) - BUT also: The Relay is nice - it is not pulling - BUT a switch on the relay is faulty (hard to detect). I try to narrow down on the problem(s), greetings Rolf

Hi Mark
great - You found the fault on 25-Cent-Relay (grumble - one of the "hard to detect" faults). So the Motor stops and the Outhole-Relay should pull-in. See the JPG - "red" is the power-side-connection - is it good ? Try the flipperbats - can You actuate them ? (You should) Try to bang a tilt - does the Tilt-Relay pull-in ? (it should) IF (if) "No reaction": Check the two switches I have marked with an "red X". ALSO: The connecting wire to Outhole-Relay-COIL may be faulty.

The Score-Motor has stopped - through my "green wires" the INITIAL-Circuitry shall be established - so the Outhole-Relay does pull-in. The Outhole-Relay closes "Self-Hold-Switch ('orange wires') - the Score-Motor runs - after a while the Self-Hold-Circuitry ("orange wires") is broken-off due to opening SCM-6A.

For BOTH actions You need a "NON-Pulling Eject-Relay" and "good switches on the Eject-Relay" AND the connecting wires must be good. IF (if, if) the Eject-Relay is mounted on the playfield: There is a Jones-Plug involved - connection playfield to bottom-board in the cabinet. Greetings Rolf

P.S. - TRY - As the Motor stops: Gently push the armature (anchor plate) of the Outhole-Relay - does it stay pulling ?

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