BX needs to activate and latch when the last ball drains. When it does, a switch on it opens, which opens the path to the Add Player Unit.

BX activates via the wiper disc on the Player Unit and a switch on the Ball Return relay (O).

(This can be found on the schematic at around 16E.)

So first need to observe if BX is activating and tripping on the last ball. If it is, then make sure the switch there opens, and there's no short on the back tabs.

If BX isn't activating, then check the wiper disc on the Player Unit to see that all the spring-loaded fingers are making good contact with the stationary disc, and that the fingers have their braided copper wires connected to join them.

The man is a "Gottlieb Whisperer"

I was following one of my Gottlieb schematics and was headed down that path, but my answer would have been so much choppier.

You're a master.

Ok, good. The next thing to check would be the switch on Q with OR-BLK and BR-BLK wires to make sure it opens when Q energizes, cutting power to O.

Here's why:

With BX latched, one of those open switches should prevent the Player Unit from stepping. And, a now closed switch on BX, along with a switch closed on 'O' (O is still energized from the ball drain), should complete a circuit that scans for a Match for each of the four players, going through the Coin Unit (the Coin Unit steps down for this).

Then a switch at motor 4C finally closes at the end of the score motor rev to complete a circuit to Game Over (Q). This is the same path as the Match check, and goes through the same switch on O and BX (but now adds motor 4C).

Once Q activates, it should open a switch on Q that opens the path to O, causing O to de-energize. If O doesn't de-energize when Q activates, then a switch on O will keep the score motor running and the cycle will just repeat.

Since O and Q are kicking in and out, that suggests that the path to O isn't getting opened like it should, which suggests the switch on Q isn't opening when Q energizes. So I'd check there next (and the back tabs, etc. for a short).

(This is at 22E on the schematic for the path to O, and at 14E for the path to Q and Match logic.)

That switch needs to be closed when Q is not energized, to allow O to energize (which in turn causes the ball to kick out). So if the ball return kick never fires, then it sounds like now the switch never closes.

It needs to be adjusted so that it opens when Q energizes, but otherwise is normally closed.

The slip of paper test was good though, as it sounds like that's at least the right switch. Just needs to open and close properly hopefully.

So another possibility is that Q is working fine (and was working fine), but the problem is actually back on O. If the armature on O doesn't let go fast enough to open the lock-in path, it might be able to re-engage when Q de-energizes.

Oh, wait, I forgot to mention something else!

When Q energizes in the sequence I outlined above, it should stay energized via its own lock-in switch and a make/break switch on AX that should be closed while AX is unlatched. So Q should stay on until the next game is started.

From the description, it sounds like Q isn't locking on and holding, so the better thing to check would be its lock-in switch and that make/break switch on AX. The lock-in switch will be the one connected to the coil lug, and the switch on AX is BL-WH-RED on one wire.

I'd guess it's the switch on AX.

I had a few issues very similar to this on my 4 player Jack in the Box, so many of the circuit paths are similar to this game (main difference is no Ax)... all good tips and spot on with those circuits so far... I would also suggest making sure the switch stacks on those relays are tightened down, and that there's no mechanical binding happening when those relays pull in/disengage.

Gottlieb relays have very little play in them and to really nail them down functionally , especially make/break switches, I use a lighted magnifying glass and manipulate the relays and eyeball the make/break action as I adjust the blades as needed.

I've also had contact points come loose on the blade, resulting in inconsistent troubleshooting - this is a corner case and most likely isn't your issue, but it does happen.

Q still energizing after the last ball drains and letting go though? It really needs to energize and lock on. So the 'energize' part is working, which is good, but the 'staying' energized part isn't working, which is the problem.

That narrows it to only the lock-in switch on Q itself, and that make/break switch on AX.

Since the switch on AX should already be closed after reset completes, you should be able to manually close Q and have it energize via that same lock-in path (without having to play the game and go through all five balls). It should click on and then when you let go, stay locked on.

If it doesn't, then that path from AX back through Q has an open in it.

If AX is in the backbox and Q is on the score motor board, then there's also the possibility of a Jones plug connection gone astray. But I'd focus first on the switch on Q and AX more.

Without going through playing all 5 balls, you should be able to just manually close the switch ladder on Q and have it 'grab' and hold.

We know the coil is good, since the activation path works, but the 'lock-in path' has an open in it still.

Do you have a jumper wire?

A quick brute force would be to jumper from the Q lock-in switch to either side of the AX m/b switch, to see if that bypasses an open. Or from the lug on Q where the lock-in switch attaches to either side of the AX switch.

Are AX and Q co-located very closely, or are they separated by cab/backbox?

Which relay? (Q or AX). There's no switch on Q that should run the score motor, but there is on AX (although it's YEL-RED on one blade, not those colors). Not sure why the score motor would run, unless AX got latched somehow.

No, I doubt it. If you jumpered from the 'far side' of both switches, then both were bypassed and a direct path to the Q coil was created. Need to move the jumper to the 'near side' of the switches, so at least one (or both) of them still need to close to complete the circuit. The 'near side' in this case would be the BL-WH-RED blade of both Q and AX (i.e., should be nothing but that wire between them). But the 'far side' of that switch on Q should be BL+BLK (and have a wire that runs over to the lug on the coil). That would bypass the AX switch, but leave the Q switch in the path.

If this isn't making sense, I can try and craft a picture later.

Did Q remain locked on? Not sure why the score motor would be running (again, unless AX got latched somehow).

Could be the armature plate isn't sitting flat on the new coil center lug, or that there's too much blade tension (and spring tension) pulling the armature back up.

Then this would have bypassed the lock-in switch on Q, but left the AX m/b switch in the path.

This would put the lock-in switch on Q back in the path.

The combo of these two tests suggests the problem is with the lock-in switch on Q.

One additional experiment would be to jumper that lock-in switch right at Q. Because space is cramped, could put one clip on the red jumper and the other clip on the BL-WH-RED side. Bear in mind though that the path from the lug (the red jumper wire) to that switch is also a possible suspect.

Seems to be right there in that area though, based on the previous tests.

Can't jumper that switch until after the reset has completed, otherwise there's a path to Game Over active right away, instead of waiting until the last ball. With Q active, the O relay can't activate to kick out the ball.

You can still jumper it early, but put a slip of paper in to block the switch until after the last ball drains and it enters that endless cycle mode. Then pull the paper out, and that path will be completed.

But yes, it sounds like there's an issue with the lock-in switch. Do the contact points spin in the blade at all? Have you tugged on the wires to make sure they're on solid?

Is that picture with the game off? Cause it looks like that lock-in switch is closed, and should be open (the switch pair that has the red jumper wire). That switch should only close when Q is energized and pulls the armature plate in.

If that switch is closed when Q isn't energized, then yes, Q will energize at game power on (via the switch at AX).

But that would also mean that the switch works, and shouldn't need the jumper.

How does it behave with that switch gapped correctly?

And it's probably an optical illusion, but are the backs of any of those tabs touching? Looks like there's one about in the middle, but could just be the angle.

If they are, then they shouldn't be.

And you're sure that after the last ball drains, Q is energizing and de-energizing? That's the weird part.

No - there shouldn't be a closed path to it following a power off then back on. That lock-in switch being open should open the lock-in path, and the motor 4C switch being open should block the activation path (assuming the score motor is left in the 'home' position). If the score motor runs briefly at power on, then Q could maybe energize.

This sounds important. I've been going by an understanding that both Q and O are energizing/de-energizing. If Q is not, and it's really only O, then need to see whether Q is really getting its initial pulse or not. It could be that motor switch 4C is not allowing the signal from O energizing to reach Q.

Following game reset (so at Player 1, Ball 1, ready), if you manually press the O ladder stack, the O relay should 'grab' the armature and hold it, run the score motor, fire the ball kicker, and then 'let go' of the armature. That works, right?

Then if you manually press down the Q ladder stack, Q should lock-in and stay on, with the game in Game Over. (Don't bother playing through all 5 balls, this is just a test of the two basic relay behaviors.)

If those both work correctly, then check the switch at motor 4C to make sure it's closing.

But Q locks on following a power on?

OK, let's see the video!

And what coil part# is currently installed for Q?

I think only links to videos are allowed, so would need to go to YouTube or such.

If you block the switch at motor 4C, then does Q lock on at power on?

Never mind - Q also gets a signal from a make/break switch on R, so Q should energize at power on and stay on until R energizes. So that's normal.

So just to summarize, there are three paths to Q:

- the power on path through a make/break switch on R (which is working)
- the normal activation path, which goes through a switch on O, motor 4C, and BX. Not sure this path is working
- the 'lock-in' path, which goes through a switch on Q, make/break on AX. This doesn't appear to be working.

After game resets, and R activates, Q should de-energize. If you then manually close Q, it should grab and lock-in. This doesn't seem to work. That means it's among the lock-in switch on Q and the make/break switch on AX.

Previously, you jumpered from AX to Q after the ball drained, and Q locked on. Where exactly were the jumpers placed for that? That bypassed whatever open there is. There could actually be an open in the wiring between AX and Q, rather than at the switches.

yeah, sorry - never mind on that. I missed the path to Q at power on via the make/break switch on R.

That's great news, and thanks for the follow-up. Makes me wonder if the issue was with the red jumper or original Q relay coil somehow, as the upgraded coil/diode shouldn't really be required to fix it. But in replacing the parts and cleaning stuff, whatever the gremlin was is clearly gone.

Enjoy the game!