The spring is external, you might either loosen the screw a bit to see if it relieves the stiffness, or tweak the spring a bit. I would first remove the spring and try the gate to see if there is a tightness or burr problem with the pivot itself. It is a screw, and it might either be tight in the hole of the gate, or the shoulder is too short and is pinching the gate. which could be relieved by removing a thousanths or so from the thickness of the gate hinge ring.
If it is tight in the hole, though, I would expect to see the screw loosening up from opening and closing the gate several times.
Actually, a loose screw is a factor in having the cylinder jam as the case rims hit the screw head, best to keep it tight. (use blue Locktite)