It's sometimes hard to know how much force is appropriate!
When I was but a mere student I was building myself a PC with an AMD Athlon (1.2GHz!) of which I was both very proud and very cautious - people had been known to crack the CPU die when installing the heatsink on that family of processors.
However, I hadn't even reached that point as I'd carefully aligned the CPU with the ZIF socket and closed the locking lever... which stopped half-way down, apparently binding on something.
Hours of careful removal, inspection, re-insertion followed - everything *looked* right but the resistance on that lever didn't *feel* right.
Then my housemate casually looked in and said "Oh! You just need to close the lever." and, to my dumbstruck horror, did so. I heard the terrifying click of... apparently, a ZIF socket locking neatly into place exactly as it was supposed to.