Chicago Coin game correct? Just check ipdb--found it. Gottlieb. Right

"If your game is older and does not have a power switch, you can install one. Get a SPST (Single Pole, Single Throw) or DPST (Double Pole, Single Throw) switch. Power rating for the switch should be 120 volts 3 amps or higher. (You should use a DPST switch, and turn both sides of the power cord off, but frankly I never do that.) Using a SPST switch just turns off one side of the power. Splice the one power cord lead at the transformer to a 4.5 foot length of 2 prong (2 wire) line cord. Technically you should splice the switch into the line cord's "hot" wire (not the "neutral" wire). The hot wire on the power cord should have "lines" molded into the insulation (as today's power cords are all polarized). Run the line cord up to the front of the game, where the switch will be located. Attach the other wire of the 4.5 foot line cord to the original power connection.

Also it's a good idea to put the switch on a raised 4" square block, so the switch lever does not protrude below the game's bottom panel. Then drill a 2" hole in the bottom of the cabinet wood, and put the wood block over the hole. Otherwise the switch can be easily broken if the legs are removed and the lower cabinet moved. Again I don't do this (I just remove the switch's nut and push it into the cabinet when I move the game), but it's not a bad idea."

"On older games that never had a power switch, I disable the Lock relay (bending the Lock relay's switch blades so its permanently "on"), and remove power going to the relay. The lock relay is usually burned up anyway, so adding a power switch defeats the relay and it's one less thing to worry about."

http://www.pinrepair.com/restore/index3.htm

Maybe explore this...