Once mine was sticking and wouldn't budge after I had taken the seat out. I loosened all four bolts holding the runners onto the car and then retightened to sort it out. I think I did one runner first doing the front bolt first then did the runner on the other side.
Its hard to describe the right way to tighten the bolts but logically you would want the runners sitting parallel to each other. Mine must have not been sitting parallel.
If you ever take the seat out of the car the runners can move independently to one another.