MINER WAS USING A PORTA-POWER AND BLOCK OF WOOD TO SPREAD RAILS ON CLINKER COOLER DRAG BOX TO EXPAND THE GAP BETWEEN TWO ANGLES. A LOUD POP WAS HEARD. THE PRESSURE CAUSED THE WOOD TO BE FLUNG OUT HITTING MINER ON FINGER, WHILE PORTA-POWER &REST OF ASSEMBLY FELL INTO DRAG BOX. THERE WAS AFAILURE OF THE HYDRAULIC FITTING.