I don't want to be "picky' or dig too "deep' here but more info is needed.
Now that you have found that crossover is the issue (they must be tested at the same sound level with the same source material to rule out any "other" differences).
What is the NATURE of the "distortion", does the tweeter sound like it is "trying" to produce sounds that are (perhaps) too low for it to work without "straining or rattling" (a symptom of feeding too low a frequency of sound to a tweeter at too high a level?).
I ask because sometimes a word or description (such as "distortion" or "it's a short" for example) can have have an unclear meaning between people of varying understanding or technical backgrounds or experience.
Speaking of "level", does the distortion "start" at a given sound level and increase with volume level (don't push it too hard!)
The reason I ask is because many crossover networks (the whole crossover) can have bad capacitors that fail "shorted" and aren't "blocking" the unwanted lower frequencies that the tweeter is not designed to handle (and MAY damage then).
Perhaps a "clear-Er" description of the "distortion" is needed here.
Unless the crossover is "potted" in epoxy, there should be a way to access individual components for testing and/or replacement without replacing the ENTIRE network.
Mark T.