TechnicalSteam has a point. I think a lot of amusement operators just don't want to take the time necessary to properly level the machine, assuming they realize that there is bubble to look at. They see the machine working and flippers move the ball and take off to the next drop point. Operators that I know near my area have decided not to put out any more pinball machines and sold the few that they had, because they think there is too much maintenance required. They like pool tables that require almost no maintenance, maybe a few video games and electronic juke boxes.