That wire color is actually green-yellow-yellow. There are two yellow stripes, the white on that particular wire doesn't count.
According to schematics of that era it should connect on the replay button (start button) switch - notice you have a non-factory red-yellow wire on that switch?
The schematic also says the other wire on that switch should be yellow-yellow-yellow (three yellow stripes).

It's possible someone has wired the switch for freeplay.

GTB_Sys80A_CoinDoor(2).png

I'm not sure if the manual is online for download - I don't have it.
The schematic I listed above was from Alien Star (system 80A game) but it looks like it's different to yours.

The below is from Q-Berts Quest and matches yours from the perspective that the replay button switch is listed with the blue-purple-purple wire shown on your switch and the green-yellow-yellow wire goes on the other lug of that switch:

GTB_Sys80A_CoinDoor82(1).png