There are schematics for Amigo and Champ on ipdb.org which were released at about the same time as Ro Go. They both use this circuit for Player lights, down to the same wire color:
Ro Go Player lights (resized).jpg
As the Player Up unit steps through the players the wiper connected to the common/yellow wire should power each of the players' lights in turn.

Is your Player Up unit advancing correctly? If you play a multi player game, does the score register correctly for each of the players?

/Mark

I’ve got this game and the schematics. The lights are tied to the mechanism that counts how many players are in the game, not what player is currently up. If you push the credit button 3 times, then 3 lights come on. Those steppers were the biggest challenge of bringing this game back to life.

You’re looking for the coin unit disc. It should be the same wire that’s tied to the “1 2 3 4 can play” lights in the lower left hand corner.

Dave

Here’s the photo you asked for. I hope it’s legible enough.

Dave

0036D606-C7A7-4477-9E11-4DAA898D32C8 (resized).jpeg

I just noticed your photo showing there is no player # being lit. I suspect that’s the source of your issue. Could always be the jones plug too...

Disassemble the coin unit, clean the contacts and contact plate.
Look for lose wires on the plate or missadjusted contacts.
A tiny drop of oil on the contact plate before reassembly, manually step up/down, and look if the lights will work then...