2 EE'S WERE SPLICING THE SECTION BELT USING A RED DEVIL PULLER, AS ONE EE WAS RELEASING PRESSURE ON THE RED DEVIL THE OTHER EE PLACED HIS HAND AT THE LOCKING DEVICE TO UN-LOCK THE RED DEVIL WRENCH. THE WRENCH SNAPPED ON THE EE, FRACTURING THE METCARPAL BONE OF THE 1ST FINGER, RT. HAND. THE UNDERGROUND LOCATION WAS AT THE SECTION TAIL PIECE.