Office Chair Assembly Issue: Tilt Mechanism Locked but Chair Continues to Tilt

Hello,
Recently, I bought an office chair and of course assembled it as it should be (this is not my first do-it-yourself chair). And a problem arose: the chair tilts as the TILT mechanism is locked in the vertical position. Of course, it does not bend completely, but to such a point that sitting on it is very uncomfortable, especially at work. In another chair, it was enough to finish the mechanism on the actuator by lubricating the actuator beforehand. Unfortunately it doesn't work here... Any suggestions what could have gone wrong? Everything is tightened to the max, so I'm out of ideas what it could be. Unfortunately, the seller will probably not reply to my e-mail until Wednesday.

And is there such a large knob from the bottom perpendicular to the seat? If so, they need to be tightened. Post a photo if possible.

The knob is there, but it doesn't do anything... Besides, when I'm sitting and watching a movie, I lean back, and when it's tightened, I have the impression that my back will break from the force that I have to put into the tilt of the backrest. Photo of what? The chair tilts as I sit on it. This is standard TILT.

Added after 9 [minutes]:


The photos show the entire mechanism

OK, because this screw works in such a way that you can adjust the resistance with it. In total, I checked at home and on two armchairs this blockade is also loose. It doesn't bother me, though, because I just have the tilt adjusted quite hard and I don't normally block it. Maybe that's the beauty of these mechanisms.

Generally, it is already one mechanism in a row, which at the beginning causes such difficulties, in those, everything was adjusted and they stand vertically when the mechanism is blocked. And here it is really uncomfortable as I almost start to lie in front of the computer. And it is an armchair strictly for long sitting in front of the computer. I know this knob for adjusting the tilt force and it does nothing in either direction. Well ... It remains to wait for the distributor's response, or hire two men to pull the actuator out of the mechanism and try to install it again.