Look carefully at the connectors themselves. The actual terminals in the connectors can fail. I’ve rebuilt connectors and found they can fatigue and loose tension or break off inside the housing after 40 yrs. frequent cause of intermittent connection.

When the score displays go out, is the high voltage still there? There should be a glow in a corner of the displays. No glow equals no high voltage. Knowing that you have high voltage should help troubleshoot the issue.

OK - I misunderstood. You're referring to the controlled lamps.

The only common signal for those lamps is from driver board 2J5, pin 2. Since the board is new, I agree that the issue is not likely on the board. When this happens, tilt the game - the tilt light should come on, and since the light is in the same column, you should see it. If the light does not come on, wiggle the wire at 2J5 pin 2 and see if it comes back. If it does, you should change out the IDC to crimp.

You could also wiggle that wire when the player light goes out to see if the light comes back. If it does, new connector.