A device for repositioning tubes in a tube rack is presented. The device comprises a base; a mount movable relative to the base in a first and second direction; an actuator for moving the mount; grippers coupled to and movable with the mount, each gripper comprising arms with portions for gripping a tube; a biasing element coupled to the mount and to the arms to be movable relative to the mount and to move the portions towards/away from each other; a blocking element coupled to the base to engage the biasing element and to block movement of the biasing element with respect to the mount against a force where the mount is moved in the first direction to move the portions towards each other and to disengage from the biasing element when the mount is moved in the second direction to allow the portions to be moved apart.