Quoted from KenLayton:Sometimes it's easier to simply replace a hacked up harness with a new one such as this:
https://pinside.com/pinball/market/shops/1041-third-coast-pinball/00510-bally-s-s-coin-door-wiring-harness
I'm not sure it needs a whole harness: Looks like the connector was just taken off (probably to be salvaged for use somewhere else). Is the other end of the connector still there in the cabinet (left-side by the tilt-mechanism)?