I was listening to a Car Talk podcast (bless their hearts, Tom and Ray, they retired a year ago!) and they were telling a story about a car owner who, becoming dissatisfied with the reliability of his car, wrote to the carmaker and asked that if the entire car were eventually replaced piece-by-piece, will it be a new car?
They said, it's like the problem of Ulysses's ship: if every plank of the ship is replaced during the voyage, is it the same ship? Or the joke about George Washington's hatchet -- "The original head was lost, and the handle's been replaced a couple times, but it's the same hatchet."
What do you think about watches? Repairs, strap changes, visual mods, things like that -- at what point does it become a different watch? Or is it always the same watch?