The one that works for me when that happens is the image of keeping my right hand (wrist pointed up) sliding along the underside of the pane of glass plane that we all use as an image for the swing plane. This makes me drop and rotate the right shoulder rather than throw the club at the ball. BTW the over the top move normally comes (at least for me) from an indecision as to whether or not I have enough club in my hands to reach my target. It tends to be a "I am going to HAMMER THIS PUPPY" kind of swing

When I am sure I have pulled the right stick from my bag, or pulled enough that I can take a shorter swing and still get there, I don't tend to come over the top at the ball. Kind of like the idea that when you are laying up you tend to hit your best shots because you aren't TRYING to do something other than simply advance the ball to a good spot on the short grass. 90% of this game is 80% mental......
Obi WunPutt