My friend with a WOZ having the same problem this is an excerpt from his email to me. "There's a sensor that literally tells the monkey when a ball is on the magnet, and if it goes out of adjustment, then the first couple times you take that shot, it doesn't let the monkey come all the way down. After about three failed shots, it defaults the machine into thinking the ball is on the magnet if the magnet energizes. It's supposed to keep the pin from registering a false virtual lock. Without it, if the shot registers both orbit switches in either direction, and ball is not stuck on the magnet, the machine gives a virtual lock. With the sensor, it registers whether the ball is actually on the magnet. So when it works, on a dribble shot that may roll through the orbit switches, but not hit the magnet, the pin knows the ball is not there. It's a tough one. Most owners have had to re-position the switch, and you only get about five chances to adjust it before the magnet heats up. As the magnet heats, it responds differently, and then goes out on thermal overload."~I hope this helps.