Abstract: A tool and method for repairing valve seats of hydraulic jacks. The valve seat cutting tool is a cylindrical shank of hardened steel with a beveled cutting face at its lower end, the upper end being suitable for engagement by a conventional drilling mechanism. The beveled cutting face, although lying in a single surface, has a forward cutting face beveled back to front at a 17 degree angle and a side cutting face beveled at a 5 degree angle increasing from left to right. The cutting faces are cut at right angles to one another. The size of tool is geared to the diameter of the valve chamber and the ball to be seated. The diameter of the tool, selected from a series of 18 of the same configuration, is slightly less than the diameter of the valve chamber and of the ball to be seated. The tool is centered by the existing recess in which the ball rests. The tool is inserted in the valve chamber and is rotated a few revolutions to square off the walls and bottom surface of the old valve seat.