An elongated track assembly is provided for disposition outwardly of and paralleling one pair of corresponding ends of a row of tubes and the track assembly includes a support mounted therefrom for movement along the track assembly. An elongated and longitudinally projectable and retractable pilot member is mounted from the support as well as elongated and longitudinally projectable and retractable tool which parallels the pilot member. Power structure is provided operative to power project and power retract the tool relative to the support and manually operable structure is provided for manually projecting and retracting the pilot member relative to the support. Control structure is provided for the power structure operatively associated with the manually operable structure for projecting and retracting the pilot structure for actuating the power structure to project the tool responsive to projection of the pilot structure from a retracted position thereof past a first projected position to a second further projected position and for actuating the power structure to retract the tool responsive to partial retraction of the pilot structure from the second projected position thereof to the first projected position thereof.
