I picked up an early 70s Japanese pachinko machine, and had a lot of fun getting it back into good working order. It's a Nishijin Super DX, the mechanism is called a Model A
First, I was lucky enough to find one used that was fully intact, aside from missing the front glass, which is pretty common. A local glass shop cut the right size for me (1/8" thick, just measure the other dimensions carefully and allow for it to fit into the frame slots). Then I spent a few evenings cleaning everything I could reach, with a few spots where I partially disassembled the back mechanism to reach tough areas.
With cleaning and lubrication it was back in working order, and I had fun playing with it and finding out it was a very generous machine that gave out more balls than one ever would in a real-world pachinko parlor.
The original machine has a very simple set of circuits where a couple of switches would illuminate a light at the upper left and another behind the center jackpot target. I decided to add a bunch of LEDs driven by an Arduino Pro Mini microcontroller.
I mapped out all the mechanisms and places I could add lights, then started a chain of wires and WS2812B lights cut from a strip. Most spots use one LED, larger ones two and the center big prize mechanism has five. Everything in held in place on back with heavy-duty plastic tape.
The Arduino is fed with an external phone charger battery, the kind used to give your cell phone a power boost when you can't plug it in.
The first version of the program running the lights is very simple, and just runs a changing pattern of colors. In the future, I'll hook up the two internal switches that indicate an empty ball supply or jackpot payouts, and make them blink accordingly. In any case, I'm pretty happy with the results: