Hmmmm... I can't believe after a week of discussion, someone hasn't taken out those two bolts yet and seen if this really does allow access to the pebbles.... My curiosity level is out of the park here guys and girls... I think maybe you need to find a Doctor that drives a C6. If he/she has access to an extracorporeal shock wave machine (ultra-sound), that might be another answer. After all, they can explode kidney stones... why not gravel stones... Just a thought...