Long story short, the laptop started overheating. After setting laptop apart to do usual thermal paste replacement - noticed few uncertainties. First of all, thermal paste was in tact - nothing to do with it whatsoever. The heatsink+fan block is loose i.e does not firmly sticks to GPU and CPU(this is joint block design back in vaio days).
First of all there is this BOSS nest - in my case one of them got detached, do they require soldering or gluing?
On the picture above the nest itself is attached to heat-sink+radiator block and is totally loose - it does not hold anything.
On the picture below you can see this detached boss nest from the heatsink block after I unscrew it. I've put it next to the hole on the motherboard just for visibility.
How do I reattach back this 'boss' nest as of DIY way?
Problem 2: The second problem is BOSS 5 nest. It has an inner hole inside which is significantly narrower. After I gave my laptop for the first repair(to replace fan), the company did not put the right screw back which I only realized just now. They've put M2 x 6mm not M2 x 12 mm as according to VPCF1 series spec https://docs.sony.com/release/MDSM/989080206_sm.pdf (page 3-3 for all screw types and page 3-6 for this unique B6 heatsink screw which is M2 x 12 mm). Effectively the screw they've put was swimming there doing nothing, surprised it did not drop out.
Funny thing is that I cannot find M2 x 12 mm on UK market anywhere :-D . I found M2.5 x12mm but it is too wide - does not fit inner hole. Any hackaround would be greatly appreciated.
It is a good powerful laptop with a screen way better than newer Mac Pros. The best screen ever seen on a laptop to be honest. However it is not worth spending over 100 units for problems I know myself, just unable to resolve as I mainly build PCs not laptops.