INJURED FELT PAIN IN GROIN AREA WHILE WORKING ONFAC #1 MOTOR. HE HAD PREVIOUSLY REPORTED PULL IN SAME AREA ON 8-14-00 WHILE REMOVING BACKUP POWER SUPPLY FROM TOP OF PLC CABINET IN KDC5 MOTOR CONTROL CENTER. DID NOT SEEK MEDICAL TREATMENT UNTIL 1-9-01. DID NOT BECOME REPORTABLE UNTIL 3-15-01 WHEN EMPLOYEE STARTED TO MISS WORK DUE TO SURGERY.