I've found the most effective thing you can do is video-tape yourself casting, and watch the little nuances of what you're doing in slo-mo (still/advance). Better yet watch it with an instructor. I've recommended this to many friends and students and the feedback has been consistently 'wow'. In fact I videotape myself regularly.
It's important to consider the angles of view so you can see all kinds of little nuances like tip deflection on the forward stop, or shock coming from the end of the backcast as it turns 180 to start the forward cast, abruptness of the power application causing shock waves, etc.
Curious - are you seeing waves in the top leg of the loop, the bottom leg, or both?