Hello everyone, I'm not sure how this slot machines electronics are supposed to work

? It leaves me with a lot of questions that I need help answering.
Hoping the community might have the answers or solutions. I an very much a electronics tinkerer and DIY enthusiast.
So I have what I think is a "Harvey's Wagon Wheel 5 Cent Slot Machine". I'm unsure of the year but is very much an antique. This was given to my Grandmother in the 1950s (because it was too old) from the Golden Nugget in Las Vegas. As she was a Dealer there.
I do understand that the main operation of this machine is mechanical and not electrical but I'm unsure how just the basic lights and sound is supposed to turn on or work on this things. It seems to be missing the power cord, and maybe a small PCB board to regulate the power? Although I'm not sure if this is too old for a PCB board and such?
Following the main grey cord

from the slot machine, one half connects to a dark blue

wire that terminates to the Jackpot buzzer and Light

. And the other half connects to a brown wire

that then splits two ways. One goes to a black cord (slightly thicker gauge). Might be the original power cord but cut? The other side goes to another brown wire

that terminates to the lights in the front of the slot (displaying the win orientation)

. I have attached a photos showing what I am talking about.