I can't install the Core i7 stock heatsink

[jofo]

I just put a new thermal paste on my Intel Core i7 920 and I cannot for the life of me get the heatsink to go back on. The four fasteners won't click into place no matter how much pressure I apply. Sometimes I can get one to make a click sound, but the heatsink will still be loose and wobbly.

My thumbs are literally too sore to try anymore. I've been at it for nearly an hour trying slightly different methods. I've followed 3 guides and I can't make it work. Would someone be willing to walk me through the process so I can make absolutely sure I'm doing this right? I don't know what else to do, short of buying a completely new heatsink.

 

[shortstuff_mt]

The owners manual has all the instructions you should need. Are you sure all four push-pins are rotated the OPPOSITE direction as the arrows? A lot of people seem to make that mistake. Is the motherboard still installed in the case? That makes it a lot harder to get the push-pins to seat. It's much easier to install and ensure the push-pins are fully seated if the motherboard is out of the case.

 

[jofo]

The motherboard is out of the case, yes. I tried pushing down on the push-pins with the arrows pointing outward as well as inward just to be sure I wasn't doing it wrong. I have no idea why it's not working.

I can put almost all of my body weight into it and the heatsink will still be loose.