[Nexus 7 General] TECK:
As many of us, I got my tablet C8O series with the missing screws. Asus decided to remove 2 screws instead of creating a proper fix, which is crazy in my books. For those having a screen lift (even minor like I did), you can fix it very easy with few parts you can get at any phone repair shop. By "permanent fix" I mean this is my alternative to keeping on exchanging the tablet until I find a so called "flawless" one.

Important: Be aware that on the new tablets Asus started to place an adhesive band on the speakers, probably to reduce vibration. I strongly recommend you to open the case from the top and work your way down on both sides, leaving at the end the bottom and slowly opening the case to avoid damaging the adhesive speaker band.

Now, on with the actual fix. First, go get yourself the 2 missing screws and 4 stainless spacers. I went to the nearest phone repair shop and the guy working there charged me 1$ for the 2 screws and 4 spacers... I gave him 5$ for his trouble. :)

This is how the spacers look:

The spacers are needed because the stock screws are too long, they also produce better friction between the screw and contact area. Originally, I tried to place the spacers between the inner brackets. That made the case not closing properly and snapped a plastic tab, so I placed them on top instead:

You will work with the 4 screws displayed above, leave alone the ones at tablet extremities. Install the spacers and screws, without having them tighten. This is where the tricky part is for actual fix. In order to completely eliminate the lift, you need to press down and towards outer side the bezel. Once the bezel is warped a little, you can tighten the screw:

The picture above shows the first attempt I had with the bezel warping. If you just press it down like I did, it will create a nasty space between the screen and bezel. Instead, I placed the tablet vertically on the table with the right side against my chest and using 2 fingers I applied pressure with one finger to the bezel to create contact with the screen, while pulling it towards outside with the other finger. You are actually rotating the bezel towards outside, while pressing it against the screen to maintain proper contact. While warping the bezel, tighten the screw. Then, repeat the same process with the next screw until all 4 screws are tight to a medium torque (don't over tighten them). Before you place back the cover, verify that the bezel has proper contact with the screen without weird spaces.

After all screws are tighten, place at a 45 degrees angle the cover to fit perfect on the worked side making sure everything aligns properly. Then continue pressing down the cover counterclockwise from the worked area to snap it into place, ending with the bottom area so the speaker adhesive band glues back properly. In this way you will also avoid snapping the central plastic tab.

Before (screen lift visible on the rear):

After:

The lift is completely gone. However, you can see a very tiny lift at the bottom of the screen near the unlock icon. That is because I did not warped enough the bezel in that area. When I will open next time the case I will fix it in 2 seconds, for now I'm very satisfied with the results.

September 19th, 2012 Update:

I got my replacement tablet today. Is a C8O and has the usual minor lift as well some bezel spacing:

I was able to fix everything easy, using the same warping technique. The screen is impeccable, no more flushed colors.