Carole, I'd also be sure to check the condition of the springs and the distance they are from the wall when the door is closed. Also (most likely the culprit) check the condition of the pulleys/wheels where the steel cable rolls across at the bend in the track. These are notorious for their bearings wearing out and causing drag on one side while the other pulley is still in fair shape. The new pulleys can be bought at the local hardware store for a few bucks and are easy to replace.