WTF, keyboard is getting loose

Or it seems, regardless this is very odd, the keyboard on my brothers VAIO here seems to be getting loose, creating flex and a hollow sound when certain keys are hit (even lightly). He has had it for 2 months, when he first got it, all the keys felt the same when pressed, maybe a tiny wee bit looser on the left side, but it was barely noticeable. The keys are (Q, W, E, A, S, D, Z, X, C) Tab, caps, ESC, ctrl and left shift were fine. But right now, I was using it the other day and noticed that those keys listed above were making a hollow sound. Now, I tested it and if I press down on that area firmly with two fingers and hold, it doesnt go down any further than it did when bought. It has always gone down just a wee bit (which is fine by me). But its very annoying when trying to type in a quiet environment because it seems to have spread, now the 1,2,3 and 4 keys are very hollow sounding when pressed.

What can I do? I have googled it up and some say to use double stick tape under that area to stop the keyboard from coming in contact with the chasis everytime a key is hit, but how do I even get this keyboard off? From the look of things, they have this model keyboard held down by screws and the screws are in the worst spot imaingable - right under the black part, that holds the LCD hinge. I am new to this. Oh, and my brother type softly so that is not an issue. But still, how does a keyboard just get loose like this? I need to find the service manual for this.

This is a Sony VAIO FS860W.

EDIT: Now it seems to be less hollow sounding. So it looks like it will become an on/off thing. But I still dont get it. what causes this? Do you guys get it on yours, even if its on occasion.