sounds like the tweeters are stuck in place by the gaskets, you will need to use something like a larger Allen key in one of the screw holes and lever it gently toward the centre, it will give eventually. Don't undo the torx screws under the grill as this holds the front plate to the magnet!
The 1212 units are not a drop in replacement and will require some surgery to the cabinet!
Best IMHO to replace like for like and save yourself the bother!
Also don't cut the cables as you don't have much to play with, best unsolder.
If you want I can take a look at the tweeters, if they are not too far gone I can have them back as new for very little!
If the speakers are old then it's also time to look at getting the amp section recapped.
Thanks!
I did the surgery, and I think I probably agree with you, in hindsight, that I should have just plunked the money on new originals. It was hard work, and the sound is definitely a little different. But, still, much more clarity and sparkle.
Still not much air. But then, I'm running 18 bits and they're pretty close to the back walls.
And who needs air when you can have that kind of timpani roll...
d.