Flatgrass,
I ended up getting it off. I made it out to be a bigger deal than it was. First remove the screws just under the horn housing. Then you have to remove the glue that is holding the tweeter in the housing.I used a pair of needle nose pliers and ripped it out in pieces. It will take a bit of muscle to get it out, but it will come. Once it's out of the housing, then unscrew the four screws on the back side of the tweeter. Once that's off, you're good to go and you'll have access to the diaphragm. It should just lift right out. Be careful not to bent the new diaphragm when putting it in. As far as glue goes to put the tweeter back in, I would guess liquid nails. If someone has a better suggestion, please advise.