I finally found it! A story that has haunted me for decades. I remembered it being some kind of TV movie. It was about twins, one of whom had died in childhood. I had a vague memory of one twin pushing the other into a well. All I remembered was the well, a doll and also the fact that one twin had a heart murmur. I've tried to remember more about it so that I could find it, but nothing ever came of my efforts. Now, during an Incredible Hulk marathon, I have found it. Season Two, Episode 14, and appropriately titled "Haunted."
Turns out that it wasn't a well, it was the water wheel in a mill. I can't believe that I didn't remember some of the other chilling aspects of this story. Like the score, which has lots of pipe organ, spooky music box sounds and a creepy lullaby sung by the dead twin. Also, it is so strange that I had no memory whatsoever of the fact that this was an episode of The Incredible Hulk. How does a big, green hulk of a guy not stick in your mind?
You can watch the entire series on Netflix.