Figure 2. The photo above shows one of the axial slots in the bolt head shaft. The slot depicted here is the one into which the rib on the extractor tail snaps when the bolt head is in the extended position. This slot should be square. The sides should be straight and the edges where the walls of the slots transition to the shaft of the bolt head should be rather sharply defined and not rounded.
Figure 3. This photo shows the other slot. This is the slot into which the rib on the extractor tail snaps when the bolt head is in the retracted position. One wall of this slot should be square with a straight side and sharp transition from wall to shaft. The other wall should be inclined at an angle approaching 45 degrees.
Bolt operation can be improved by polishing the surface of the bolt head shaft between the two slots.
Examine the slot that corresponds to the extended position - the one with the straight walls. The bolt head should be replaced if the edges where the walls transition to the shaft of the bolt head have become rounded.