EMPLOYEE WAS INSTALLING A WALKING BEAM IN A LUBE TRUCK. HE WAS RAISING THE BEAM(ONE END) INTO POSITION WITH THE AXLE HOUSING USING A 3/4TON COMEALONG. EMPLOYEE WAS UNDER THE TRUCK WATCHING THE ALIGNMENT. AS THE BEAM WAS LOWERED INTO POSITION, THE BEAM GOT STUCK.ANOTHER EMPLOYEE TAPPED THE BEAM W/A HAMMER-CAUSING THE BEAM TO FALL TO THE GROUND ON INJUREDS FINGER.SLACK IN COMELONG.