When 10 points is scored, a 10 pt relay switch will close and send power to the No Match Step Up solenoid and the No Match Alternating switch will close and open Then power will be sent to the Change Relay coil. A make/break switch on the Change Relay will open/close to alternate power on the left/right jet bumper lamps and the center jet bumper lamp. Power to the Change Relay switch is provided through the bonus unit.
Check the bonus unit to see if the rotating switches that provide 6 volt power are fully advancing to the final contact rivets on the bonus unit stepper. The 6 volt power would move from the bonus unit using the red/yellow wire and red/blue wire.