I had the same problem when my front block got twisted to the left. Loosen that screw up SLIGHTLY and tweak with it until your trigger pulls smoothly. Then hold it there and tighten the screw back up.
Oiling your 3-way won't help if it's in the wrong position. There's too much force to one side on the trigger actuating rod; This can be easily solved by moving the whole front block either to the left or to the right.
You can't move the front block left or right, you can rotate it left or right. If that was the case it probably wouldn't stick, it would just not move it all. But that is a possibility.