I am selling an office chair for computer work, 35 лари

I bought it here at the flea market as a temporary one. In my opinion there is something with the gas lift, because it keeps sinking (maybe you need to rotate something there, I don’t know). At a height of 173 cm it was comfortable to sit; the previous owner assured me that it worked but I don’t know. Externally it’s fine, except the upholstery, it has some pills and wear, you could put something over it.