Quoted from Eskaybee:There's two connectors that go to the ball trough opto board. Reseat them both with the power off and you should be good to go. location is right at the entrance to shooter lane under the playfield.
Very common problem with sterns that occurs probably once or twice a year in HUO environment but happy to know stern is finally addressing this issue moving forward.
This is what it was for me as well. Those two pin connectors loosen up from the vibrations.