Zalman cnps10x optima fan crackling?

Question

Cooling systems

Good day, dear ones. zalman cnps10x optima was purchased about a year ago. A crackling appeared a couple of weeks ago, the crackling comes from the zalman cnps10x optima fan. It appears when the system is loaded, but not always. I checked if the blades are touching anything - they are not touching. I took it off, cleaned it, blew out the dust, put it back, but crackling began to appear less often.
When it starts to crackle lightly with my fingernail, I press the fan itself into place above the magnets inward (the circle to which the blades are attached), and the crackle instantly disappears, let go - it appears. The fan itself is not collapsible, the type of bearing is hydrodynamic. Can anything be done to him? And what could be causing this noise? By the way, in the BIOS I wanted to find the rotation speed at which it cracks and turn it off simply, I poked all 9 modes - there is no cod ... help me pls