Sorry Rich_P, I did reply to this back on the 3-4th for some reason the reply did not post.
Yes, topping is almost always flipping or trying to hit at impact vs. maintaining the "setup" shape as the body rotates to the finish. The best approach is to shorten the backswing so you can learn to rotate through impact with a flat (to even bowed out), front wrist... being supported by the back wrist. You want to take 50 yd. shots so you can control the urge to hit at the ball. You want to feel this shape at impact as the body keeps turning. You can even feel the body moving that shape around to the left through impact. You want to feel like the shaft is still in line with the front arm as you turn. As, you get more confident, you can lengthen the backswing and rotate a little faster to see if you can still keep from throwing the club head. Takes practice, but will come if you give it time. Drills: The Finish Drill, The Fixed Wrist Drill, The Large Muscles Drill, The Stop Rotate Drill... these all keep the hands fixed as you learn to let the body do the work.
Move Less ... Get Good! DUPLESSISGOLF