have a Williams Blackout and when start a game and Press the right flipper (just once) it will make a "joust sound" from the sound board and then lock up all the playfield. The flippers still work but nothing else does.
If I unsolder the diode on the right flipper then the game all plays great (left and right flipper function normally). But of course I do not have any lane change on the right flipper.
I have swapped a good MPU board in thinking that was it (it was not) , where else should I look?
P.S. The Diode seems to test "good"