An apparatus for positioning a flexible lance drive device in registry with an opening into a heat exchanger tube sheet includes a flat plate bracket adapted to be bolted parallel to a flange of the heat exchanger. The bracket carries a stub tube fastened to and extending normal to the flat bracket. A rotary drive is removably fastened to the stub tube and has a rotary disc rotatable in a plane parallel to the tube sheet. A slotted box rail has a proximal end clamped to the rotary disc and a linear drive assembly is removably fastened to the slotted box rail. A guide tube collet block assembly clamped to the linear drive assembly removably supports a flexible lance drive and guide tube to guide a flexible lance between the lance drive and a selected one of a plurality of tubes penetrating through the heat exchanger tube sheet.