I am not sure about the time on them, maybe 2-3 hundred hours...
Your speakers are not yet broken in, your speakers are not yet broken in, your speakers are not yet broken in. Oh yeah, and another thing: your speakers are not yet broken in. check the manual...3-500 hours.
I think that changing the tweeter would be the easiest but I will be open-minded
You've been given suggestions about checking the crossovers, speaker placement, speaker cables, and allowing the speakers to break-in, and yet...
I think I'll try some ribbon tweeters
So why did you even ask for advice?