I have a strange problem with the auto plunger on my Who Dunnit. Sometimes when multiball starts 2 balls are served to the shooter lane before the auto plunger fires. Shooter lane switch is registering every time in switch test ( with a ball! )but I changed it anyway along with the diode just to eliminate it completely. Re-seated ribbon cables. At least 50% of the time the auto plunger doesn't fire until the 2nd ball is also in the shooter lane. I've looked at the trough opto's and all seems fine there. Whats strange to me is this only happens in multiball, never in single ball play. In my mind if there was an issue with the shooter lane switch or any of the trough opto's I would be seeing 2 balls in the shooter lane more often, not just in multiball. Any help appreciated.

Thanks

Kev