I see the good players seen this:
Ball heads toward a out lane:
Open hand, quick palm punch to the corner of the lock bar, one hand, on the side the ball is draining. Not super hard, but very sharp.
Alternative is a open palm slap to the side of the cabinet, on the side armor and cabinet just below (near flipper button). Again, not super hard, but sharp. Depends on the angle the ball approaches the outlane.
Timing is everything! You have to move the post JUST BEFORE the instant the ball hits it.
The reasoning is that the ball is going toward the drain and you need to time your slap or punch to move the post as the ball hits it. This puts MORE energy into the ball, but can change its angle and speed, hopefully popping it out and away from the drain, or at least to get it off its trajectory.
Rarely, on games with insensitive tilts, you can try a shaking motion, and hope the balls 'wanders out' of the top of the outlane. Rarely works because the balls has already slowed and lost energy.
Have fun experimenting. If your hand hurts, you are not doing it right.