We hang out the rear wheel.
We move the protective cap with a beard and remove it.
Straighten the ends of the cotter pin with pliers and remove it from the hole in the trunnion and the grooves of the castellated nut.
With a "24" head, we tighten the bearing nut to a torque of 25 N • m, while simultaneously shaking the wheel several times in both directions by hand to align the bearings.
We loosen the tightening of the nut to the position in which..
... with a screwdriver, you can move the thrust washer in the radial direction. In this case, the blade of the screwdriver should not rest on anything.
We install a new cotter pin and bend its ends. If the groove of the castellated nut after tightening does not coincide with one of the two mutually perpendicular holes in the trunnion, then turn the nut until its nearest groove aligns with the hole in the trunnion and insert the cotter pin. If at the same time the washer is locked, then remove the cotter pin and loosen the nut until the locking elements are aligned. Install the protective cap in place. Before installing the protective cap, put grease in it.