WHILE ROOF BOLTING WITH A STOPER ROOF DRILL, INDIVIDUAL HAD JUST COMPLETED INSTALLING THE ROOF BOLT. WHEN HE WENT TO LOWER HIS ARM IT WOULD NOT COME DOWN. INDIVIDUAL PUSHED AND FORCED ARM DOWN , FELT POP & PAIN. FOLLOWING AN MRI & DR'S APPOINTMENT ON 6/16/03 FOUND HAD SMALL TEAR TO ROTATOR CUFF IN RT SHOULDER. WILL TREAT W/THERAPY. HAS NOT MISSED ANY WORK, REPORT DUE TO POSITIVE DI