It just seems from the pics and your comments fifty that there have been a number of changes(hacks) to your machine so that may mean normal logic to why the game is not working is not applicable or more difficult to trace. You have mentioned relays in different places according to the labelling but I am bewildered by some of the 'foreign' relays included in your post 35. I would go back to the start routine for this machine (do you have the manual) and before you change anything try to grasp how far you get on the start routine and then work step by step. Wholesale change despite the best of intentions can often bring wholesale new problems as already indicated by HowardR and curriedog).
Some time ago our revered colleague dirtflipper posted this simple task checklist which I have always found a good starting point-
"Maybe the thing to do is to begin at the beginning:
- manually reset all score reels to zero
- manually reset all relay banks
- unlatch any interlock relays
- have a credit on the credit unit
- place the ball in the outhole
- press the start button
What happens?"

When you purchased the machine fifty did you get any feedback on whether the machine had worked. I guess what I am suggesting is that even before you start 'returning the machine to factory' try to better understand what it will do and what it will not. Often returning to factory is easier said than done and as has been said previously any further change can bring about unintended consequences to further cloud the resolution. By using the start routine as the prompt that should give a step by step approach as you gain info to make logical decisions. On the other hand I am conscious that many hacks did not result in a working machine and in that regard adopting a logical course forward is fraught.

From that exercise suggest you try manually advancing the player unit.

Not many places that detached wire can reach. Try an arc and see where it leads-perhaps that first left terminal on the female jones plug.