I have a 6 month old Chessie who is very birdy, loves water, and will run to a retrieve at full speed. However, on the return, he either does not want to deliver to hand or does so very reluctantly. Does anyone have advice on how to correct this problem?

Just make it fun for the puppy, throw in the water ,on the return start running away from the dog and acting silly bend down inticing the puppy to come to you reach out to grab the dummy,once you got this down pat the puppy will see how much fun it can be.

Patrick,
Your puppy is showing great natural abilities. Now it is up to you to harness that ability. 6 months is a great time to begin the transition to retrieving YOUR way. Start with basic obedience involving heel,sit,stay. Arrange your fun retrieving to insure success. After the dog knows what a collar and leash are all about use a check cord so he must come back to you EVERYTIME then you will progress to forcing to hold etc.
The fun has just begun start now to avoid bad.
Tim habits.

I think this is where force-fetching comes in handy. But she might grow out of it a little. My 7 1/2 month old is slowly getting the idea of bringing to hand. Each day he is a little closer.