Hey all -
Need help decoding a phrase on my Big Ben schematics -
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In this bit, the bottom switch is labeled "DRUM UNIT ZERO POS.SW(4)". I thought this may refer to the zero position on the score reels, but no - those are elsewhere, and named "xx POINT D.U. OPEN@ ZERO SW".

Am I correct in assuming that there is a second switch on the score wheels, the (4) is a quantity (10,100,1000,10000) that should all be open when at zero? Or is there another 'drum unit' it may be referring to?

(The issue, for context: Starting a game, score motor will engage, and score will reset to 0. Bonus will reset to 0. Ball count will reset to 5. And the motor continues spinning - the relay that resets everything - conveniently named the "RESET" relay - isn't unlatching when everything IS at zero and ready to go.)

Will be poking at it later today then, see what I can find. I am definitely getting a closed circuit between the reset relay coil and the black feed (the vertical circuit line on the far left of the image there), and have checked the score motor switch and the bonus relay switch - both of those are open when they should be. So the issue is either a shorted wire elsewhere, or that 'DRUM UNIT ZERO' switch.

Thanks guys!

Okay, just to document my path here..

1. Inspected the Score motor switch. It's good. (Relatively speaking. Someone at some point tried to bend it improperly, and it looks a little misshapen. However, it makes good contact when it should.) No shorted tabs, either.
2. The switch on the "Bonus Relay" is good. No shorted tabs, either.
3. Checked all 4 Score Drum switches. No shorted tabs, and all looked to open on "0".

Switches #1-#3 are interrupted to the coil by the self-latching switch on the Reset Relay. That switch is good as well, no shorted tabs, and it closes and opens firmly.

That leaves the switch in the Coin Relay - which bypasses the self-latching switch. So as long as the coin relay switch is closed, the reset relay will stay energized.

Sure enough, the "Coin Relay" is staying energized. If, during the repeating reset loop, I manually deactivate that relay, the RESET relay will dro, and game will go into play mode.

So, THAT relay is fed by:
1. A switch on the 'GAME' relay,
2. Two switches on the score motor. (One for 3 ball, one for 5 ball.)

#2 was easy to rule out - simply disconnect the 3/5 ball play plug. That will stop either of the two motor switches from locking the circuit closed. And with it disconnected, that did not fix the issue.

That leaves the GAME relay. Switch was fine, as were the tabs. Start a game and watch - the GAME relay is not picking up. .. Aaaah...

Now to find out what feeds power to the GAME relay.

Luckily, I was able to easily rule that out, as I have no coin door at the moment. This is why I jumped to the next stage, the 'GAME' relay..

Yup! So, I started looking at the 'GAME RE. LATCH', which is the coil that wasn't energizing when it should have been. I started looking at the ball count unit. My game had some odd changes made to it in its past life, and looking at it, I noticed that one of the wipers wasn't straight. However, turns out that that wiper isn't even related to my issue. The two wipers that were.. seems fine. Continuity at ball index 0, as expected. Jumped back to the Coin Relay, as it has a switch in series. That checked out as well. This is the part I'm looking at now:
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Which made me want to ask:
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What is the "C" there mean? It's not a listed wire color code. And the "IND A" tells me it's the Index cam, switch A. This is correct - took the Index switch stack off, bottom switch stack has a Red-Green and Black-Yellow on it. THAT also checked out.

So, that means that somewhere in my Red-Blue wire, I'm losing continuity. At this point it also occurred to me that the Red-Blue is likely going straight from the ball count unit to the credit unit. So, start looking at the wires there - found it!

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This picture is taken after I moved the wires around, but there's some odd cut in both Red/Blue wires here, where then all four were twisted back together. I haven't technically fixed it yet, as I'm going to do it right and all (and ran out of time today to take care of it). But, I know what I'm doing tomorrow after work. And this should fix it then. Whew.

Thanks guys for the pointers, it helped me follow everything through and get down to it.

Thanks guys, again -
Yup, patched that wire up and it corrected the issue. Still have an intermittent issue - likely related to the ball count unit, but I'll address that later.

Thanks!