Quoted from drsfmd:I can't remember which game it was, but at one point a game passed through my collection where the match unit stepped up by 1 just as you say, but the numbers weren't in order-- essentially making it "random"
The numbers are not in order. The schematic shows the order.
We used to think there was a sensor in the door that gave a match when detecting that we'd moved away from the game, to draw us back.