ON 6/27, EE REPORTED TO HIS SUPERVISOR THAT HIS BACK WAS SORE AND HE NEEDED A COUPLE TYLENOL. HE SAID THE 40 TON TEREX HE WAS OPERATING RODE ROUGHER THAN THE CAT 777 HE NORMALLY OPERATED. HE F INISHED THE SHIFT AND WORKED 6/28 WITHOUT INCIDENT. HE REPORTED THE INJURY ON FRIDAY 6/30.