EE WAS REMOVING A FILTER COVER TO REPLACE A FILTER. WHILE DOING THIS, HE FELT A POP IN HIS LEFT SHOULDER. THIS INJURY WAS NOT REPORTED TO HIS SUPERVISOR UNTIL 3/4/04 AND EE WAS NOT SENT TO A DOCTOR UNTIL 3/9/04. AT PRESENT, EE IS ON MODIFIED DUTY, BUT MAY BECOME AN LTA.