This is a story from Analog Magazine about the 1990s.
An English professor made his reputation critiquing the stories of a dead writer, especially one particular story. The story opened in class when a student pointed out that the entire meaning of the story would be different if the first letter of a particular word was different, and wondered if that was the case. The professor said he was wrong, but wondered.
After obsessive research, he still couldn't tell the first letter of that word, since the original manuscript had both letters superimposed in that space, and he couldn't tell which had been typed first. His friend in the physics department told him they had just invented a method of communicating with people in the past.
He communicated with the writer, who was upset that her early death from a heart attack meant she would never enjoy her fame, and she was angry that he cared more about understanding her story than warning her to avoid death. She didn't tell him, and she was careful to type both letters in the manuscript so no one (not even we the readers) would ever know.
Then she began exercising and dieting to lose weight and try to avoid her heart attack and enjoy wealth and fame. Unfortunately, she overdid it and caused the heart attack she was trying to avoid.
Does anyone remember the title, author, and issue?
