The shafts are hollow on the Z2. I had a cue maker replace mine and he didn't know that it was hollow. He was cutting the ferrule down and all of a sudden the whole end of my cue was gone. My jaw almost hit the floor and almost killed him. He had to dig all of the silicone stuff out of the shaft( I don't think it was silicone) and make a tennon to fit in the end of my shaft. He put a lot of epoxy in it and let the tennon set up and then he put a longer ferrule on it.
It totally changed the hit of the cue and I've learned to deal with it. The reason I had it changed is because it was cracked. I got i back in '08.
Send your shaft back to Predator for repairs or to someone that you know for sure can fix it properly.
The ferrule is cracked, but the tenon is fine, so gluing on a new ferrule should work as long as I get a ferrule that fits. Thanks for your input. I have started a thread on "ask the cuemakers".