I dont know the layout of your ZIF socket, but on my KT7, I actually had the HS turned 180 degrees from where it should have been. youll note on the CPU contact surface of the PAL that there are 2 sides that are...whats the word...scooped out? milled down. This lets the HS clear the one raised portion of my ZIF socket...it was resting on it, not even touching 2 of the pads on the CPU. Didnt crack the core or anything, its running just fine now. I made sure a few beers were applied to keep the hands calm before removal and re-instalation....
[Edit] Oh yeah, dont worry too much about cracking the core, just dont rock the HS; keeping even pressure applied downward while attaching the spring-clip helped a lot. Doing this outside of the case helps a lot.