EMPLOYEE WAS HELPING REPAIR THE R-BOLT MACHINE. HE WAS USING A LARGE WRENCH TO REMOVE A CONNECTION ON THE MACHINE, AND IN ORDER TO DO THAT HE PULLED UP ON THE WRENCH FOR MORE LEVERAGE. WHEN HE DID THAT HE FELT PAIN IN THE GROIN AREA. EMPLOYEE JUST RETURNED TO WORK FROM A SIMILAR INJURY AT ANOTHER JOB SITE. HE RE INJURED AN OLD INJURY.