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Your best bet is to find good, used replacements and swap them out. The ML system is matched and the amp is a little sensitive to speaker ohm ratings.
The tweeters can be disconnected, but you'd have to open up the dash to get at the connectors. If you're in that far, might as well swap them out...
Speakers that buzz almost certainly need to be re-foamed.
I re-foamed my front speakers and the buzz is gone.
I used these 6" speaker foam rings. https://smile.amazon.co.uk/gp/product/B07DDLBY96
I've refoamed my front left and front right speakers once, and subwoofer twice, using the kits from SimplySpeakers. No need to replace the entire speakers, aftermarket speakers don't match the factory signal calibration, and new speakers are rather expensive.
Replacing the tweeters "properly" involves removing the dash. You could probably hack apart the openings for an easier time, but it may not look original when you're done.