it looks like a pretty thorough rewiring, so it's not likely that a bally schematic will match the wiring very well.
however, the companies that did this kind of stuff usually followed the bally circuit design - at least partially. It's a good bet that the orange wire is the 50V (probably) power and yellow wire is the common.
in this case, the dashpot switch is typically in the handle release circuit, so I'd:
1] deposit a coin so the coin relay powers
2] grab a meter and stick one probe on the orange wire (70) on the stepper unit in the top, poke both sides of the dashpot switch. Got 50V?
if you have 50V at the dashpt switch, then the game is to see what is in between the dashpot switch and the handle release relay. You might be able to trace the wires, and if not checking for zero ohms on ends of wires of the same color is a not guaranteed but a good bet you have probes on ends of the same wire.
if you don't see 50V on the dashpot switch and the game doesn't pay, then switches on the reel mech A and C and handle release relay switches are often in the circuit.
their use of microswitches for the reel mech A-D switches is interesting. You should see zero ohms with a probe on the blue/something wire on the A switch (bottom left microswitch) and other probe on the red wire on the C switch.
with a probe on orange wire 70, you should see 50V on all the wires on the reel mech A and C switches when the reels aren't spinning.
it's possible that someone was guessing where the wires attached on the microswitches and screwed it up. They all have a common lug and a NC and NO lug which should be marked on the case. However, ya gotta see how the switch operates. For example, reel mech A and C switches are both logically NC, but at rest the lever is in different positions for the two switches, so they are wired differently.
I'd guess the common lug is on top, NO is the middle and NC is the end.