a scanning probe microscope equipped with a mechanism for exchanging a probe balance beam from the scan head , wherein the probe balance beam is of the type which is magnetically constrained on the scan head . a magnet having a magnetic field strength greater than that of the scan head magnet is utilized to overcome the attractive force exerted on the balance beam by the scan head magnet and transfer the balance beam from the scan head to a plate in a holding station on the sample table of the microscope . completely automatic operation is achieved without operator handling of the balance beam .