Abstract: An electron discharge machining (E.D.M.) tool combination is useful for removal of an installed nuclear steam generator tube plug of conductive material. A conductive wand shaft connected to an E.D.M. voltage source is movably mounted in a housing and insulated from the housing. An inlet adapter is mounted on the wand end and connected to a source of deionized and demineralized water to provide a dielectric fluid and removed material carrier. A hollow electrode is mounted on a hollow extension beyond the end of the wand and inlet adapter in fluid communication with the adapter for movement with the wand relative to the housing. A drive plate is moved by means of a ball nut along a roller ball shaft which is rotationally driven by a motor in the housing. The drive plate reciprocates the wand and electrode for E.D.M. operation. The wand position can be monitored remotely by a signal from a potentiometer with a tap movable with the wand.