I've been working on retraining the retrieve for 2 weeks and my dog still chews and pounces on the dumbbell. I have been following the instruction in Training the Retrieve with Michael Ellis. How do I address these issues?

I recently bought Michael's DVD on teaching the retrieve. She's all about retrieving, but she chews on the dumbbell. I switched to the pvc pipe like Michael suggested in the DVD. I've been working with her for two weeks using the pvc pipe and I'm not seeing any change in the chewing. I've tried reinforcing the hold by giving the command again and using my hand under her chin to hold her head up. She still continues to move it around in her mouth. Also, she's a maniac when she runs out to retrieve. Sometimes she overshoots the dumbbell and then pounces on it like it's a toy. How should I address these issues? Thanks!