There is already a good question about fixing a jammed zipper. I have a different zipper question.
A nylon zipper on a favorite pair of shorts will not stay closed. After zipping it up, it looks fine, but will soon open itself up in the middle.
I spoke with a friend who is known to be a talented seamstress, and she said nylon zippers cannot be repaired, and that the zipper will need to be replaced. She said that doing so is a difficult and time consuming task.
Is there a way to fix a nylon zipper with this issue?