I would try removing light bulbs on the play field and disconnecting wire connectors ( under the play field) in a methodical manner. Disconnect / remove the lights associated with the ones you are seeing problems with. After removing each light bulb/disconnecting a wire connector, check to see if the problem went a way. I had a similar type problem and found it to be a loose piece of solder across the wire terminals on a light socket. The ground fed back and caused a similar issue. Good hunting. Sully