While attempting to remove the feed-end door on Finish Mill #2, IE and another EE were taking turns swinging an 8-lb. sledgehammer to try and break the door loose from the gasket. While IE was swinging the sledgehammer, IE felt a pop in IE's R shoulder that caused pain. Diagnosis is ""Labral Tear in R Shoulder"". IE will work until surgery repair scheduled for 04/20/20.