Sorry if this is a repeat post but looks like the first one didn't appear so I'll try again.
Hi Rolf, just want to make sure we are on the same path.
In your post # 50 you state:
"As long in time as the pin is busy stepping down the Bonus-Ladder: The Outhole-Relay is not allowed to pull-in"
So what you think is happening is:
Ball drains and bonus count begins. If the outhole-relay pulls in during this, the game thinks the ball is still in play. As the score has now changed and the drain switch is closed (because ball is still drained). The game triggers the ball count unit as though ball was played. Correct?