The wiring on these is to a very high standard, and I'm convinced that either Arthur Jamieson or Mr. Binns had GPO experience. It would be best not to re-wire anything that hasn't been interfered-with by outsiders.
Can you post a picture of the inside of the machine? The back panel with the door open, the back of the door and the back of the door with the coin acceptor flap open?
These machines run entirely on a logical basis. There is no random element. Everything which takes place during a game cycle does so in strict order, so anything NOT happening can easily be traced simply by working logically.
Once you have the electric supply, and the main controller turning, the rest will follow.
(I avoid working late at night. You need to be clear-headed!)