In this contribution, we provide a constructive way to transform a generic Lagrangian mechanical control system into the well-known Byrnes–Isidori normal form. Then, we restrict ourselves to the underactuated two-joint-manipulator in the horizontal plane. That system fails Brocketts condition and thus achieving point-to-point control is a challenging task. The system is analyzed in normal form coordinates, which allows to design a subordinate sliding mode controller and identify three discrete symmetries. Using these preliminary steps, finally a maneuver-based control scheme is proposed for equilibrium transition. Thereby each maneuver corresponds to a suitable sliding surface defined in normal form coordinates.