Help with a swing

Can someone out there help me adjust my sons swing? I have no problem as a coach helping other kids on my team but I need someone outside to help my sons swing. He seems to be hitting the ball more and more latley down by the handle. He is still making good contact one or two times a game but the other two at bats he seems to be jamming himself or just flat out hitting down the handle. It's to the point where he actually cracked the composite part above the grip. I would also like him to have a little more power. If you have any drills or advice for me please let me know. Thanks. Bill