i once had a girlfriend who threw my pair in a pile in the front yard. busted several of the discs. they still worked. it is very hard to test those tweeters. they read open with a multimeter. they cross over at such a high frequency, most humans can't hear them to begin with. the only way i know of to check them for sound is to connect them directly to an amp at very low volume for a very short time. if they make sound, they are working.
i saw a parted out set on ebay a couple weeks ago. i think the super tweeters wound up going for just shy of a hundred bucks, but i didn't really follow all that closely.