EE was kneeling beside scoop changing a steering jack, when the new jack rolled off top of scoop. He attempted to catch the jack and strained his shoulder. The ee contuinued to work at full duty until 4/25/11 at which time he called the mines and stated he had gone to the doctor and would be off work for a week. This accident became reportable as of this date 4/19/11 days off work.