Since you didn't share what kind of speakers you have, I don't know anything about the crossover engineering of them either! 
But the easy way to find out would be to swap the tweets. If the problem follows the driver, then it's the driver. If the problem stays in the cabinet, then it's the crossover.
But the easy way to find out would be to swap the tweets. If the problem follows the driver, then it's the driver. If the problem stays in the cabinet, then it's the crossover.