Just to speculate on what may have weakened the fin on the past has anyone considered the affects of high winds on the ground.
I seem to recall, a 747 was moved, sideways, some distance by the 100 mph gusts
at London Heathrow during our famous October “hurricane”.
This A300 may have spent a lot of its life on the Carribean sectors, perhaps more exposed, than most, to buffet from high winds whilst parked.
I doubt if the airline would keep any records of exposure to such conditions, unless actual physical damage was identified at the time.