Today has been a good day, a very good day. I finally solved the issue with the "Coin S.U." Disc unit. In the end I didn't need to de-solder all the wires and take it out, it just needed some care and attention. I spent ages looking at this unit and fiddling with it. I also looked on the schematic and also a useful diagram of it in the Manual.
The manual helped as it showed be were the 'reset' position should be and so I knew where the reset coil should be turning the disc back to. It just wouldnt work, I messed with the main spring and also with the other springs on the unit (even though I knew these didn't come into play for the reset) - the two long springs were very weak and tired, so I replaced with the best alternative new springs I had anyway. This did have a good positive effect, the step up operation become much more smoother and works now very well.
I still couldn't figure out why the reset was so weak, and I was just about to take the plunge and get the unit out, when I noticed the problem - it had been there all along staring me in the face as plain as day. In fact the problem had already been spotted by me, but in a different context, and, my poor brain hadn't been clever enough to put 2 and 2 together.
Here is a pic of the problem:
Here is a pic of it sorted:
That's was it - simples! - The switch arm was on the wrong side of the bar that is on the turning wheel. I suspect someone has meddled here trying to fix a problem and that they didn't correctly figure out what this switch is supposed to do and how it really works.
The switch is a normally closed switch and it should only open when this stepper unit steps to its last position, which is player 4. Once a 4 player game has been selected (by pressing the start/replay button 4 times) then this switch is supposed to open to stop you using up any more credits, until the current 4 player game is over (or the power is switched off).
It took me a while to correctly set the switch so that it opens only on that 4th player position. It had been badly bent as a result of being on the wrong side of the bar - the reset operation trying to bend it even further down than it was ever designed to go.
So now I can start a game correctly and consistently for any number of players and the game plays out just fine.
That's a massive result for me this week and I can now dedicate some real time and effort to figuring out this intermittent problem with the score motor cam switches not stopping in the right place. I just know this is going to take some real time and effort to get fixed. I plan to start with a full clean of all the switch contacts. I'll do a stack at a time and then test to see what happens.
The manual helped as it showed be were the 'reset' position should be and so I knew where the reset coil should be turning the disc back to. It just wouldnt work, I messed with the main spring and also with the other springs on the unit (even though I knew these didn't come into play for the reset) - the two long springs were very weak and tired, so I replaced with the best alternative new springs I had anyway. This did have a good positive effect, the step up operation become much more smoother and works now very well.

I still couldn't figure out why the reset was so weak, and I was just about to take the plunge and get the unit out, when I noticed the problem - it had been there all along staring me in the face as plain as day. In fact the problem had already been spotted by me, but in a different context, and, my poor brain hadn't been clever enough to put 2 and 2 together.
Here is a pic of the problem:

Here is a pic of it sorted:

That's was it - simples! - The switch arm was on the wrong side of the bar that is on the turning wheel. I suspect someone has meddled here trying to fix a problem and that they didn't correctly figure out what this switch is supposed to do and how it really works.
The switch is a normally closed switch and it should only open when this stepper unit steps to its last position, which is player 4. Once a 4 player game has been selected (by pressing the start/replay button 4 times) then this switch is supposed to open to stop you using up any more credits, until the current 4 player game is over (or the power is switched off).
It took me a while to correctly set the switch so that it opens only on that 4th player position. It had been badly bent as a result of being on the wrong side of the bar - the reset operation trying to bend it even further down than it was ever designed to go.
So now I can start a game correctly and consistently for any number of players and the game plays out just fine.
That's a massive result for me this week and I can now dedicate some real time and effort to figuring out this intermittent problem with the score motor cam switches not stopping in the right place. I just know this is going to take some real time and effort to get fixed. I plan to start with a full clean of all the switch contacts. I'll do a stack at a time and then test to see what happens.