X1850 faders scrolling feel resistance

Hi guys,

At first i have noticed that not all the faders of my brand new x1850 feel the same. 2 are softer and 2 are harder.

I was wondering how (and with which part) can i replace the faders to make the faders feel ultra light exactly like the crossfader.

I dont like the resistance in the feel and i love “air” fader movement like my DJM900NXS2.

Any idea on this?