Reinstalling Core i5-2520M CPU in CoreHT PC

I'm trying to reinstall the CPU onto the MB in this CoreHT PC I have.

I've got a CoreHT PC, pretty old new, which I still use connected to my TV. Recently the CPU fan has been running loud most of the time, and after cleaning out dust didn't help, I decided to see if the heatsink paste needed replacing. So I remove the CPU fan.

What I hadn't realised is that CPU/fan is one assembly that all comes out together. Now I'm trying to reinstall it and having issues.

The CPU socket is a ZIF type with a screw to turn to secure the CPU in place. But the heatsink completely covers this screw when I go to install the CPU.

So I'm trying to work out how to do this. Should the screw simply be in a particular position when I screw the cpu/heatsink down? Is there a way to turn the socket-locking mechanism once the CPU is in?

Thanks in advance for any advice.

OK, that has worked.

https://imgur.com/a/73QTQJN

The CPU was secured to the heatsink, but I was still able to separate them, clean them up, then re-install them one after another.

First the CPU into the ZIF socket and securing it, then applying a little heatsink compound, then screwing the heatsink down on top of it.

I'm still not convinced the two were ever intended to be separated, but all's well that ends well!
Early days, but I think it's running quieter now too. Mission accomplished.