Razer Iskur Disassembly - wobbling

You mean the backrest has a lot of "freeplay" when you move the chair while grabbing the upper part? I think I have a similar concern as you as well...though I have tightened the screws to the backrest.

Yes thats the problem. I fixed it a lot by removing the plastic parts from the left and right side and tightened the original bolts and its fine now, they were really loose... I mean the plastic cover of the metal "hands" shown 0:20 of the video. Which I didnt find how to fix it is the chair is not stable on the part H and J on the video is still wobbling a little bit but I think its because the chair is heavy..

Yes you do have a point there. I immediately re-tightened (my poor plastic covers getting ruined) the bolts and the backrest wobbling is much reduced, albeit still visible (around 2-3cm of free play compared to about 10cm previously). I was rather shook when I first uncovered the plastic side covers, as some of the bolts were actually loosened through the excessive free play I had on the backrest. The backrest is rather heavy as well, hence that may have contributed to it. But as per the manufacturer's recommendation, we should inspect and check the bolts and joints every 60 days or so. Since I'm concerned it might one day get too loose and come apart over time.