Centre of Mass and Rotational Motion

A roller is made by joining together two cones at their vertices 0. It is kept on two rails AB and CD, which are placed asymmetrically (see figure), with its axis perpendicular to CD and its center O at the center of line joining AB and CD (see figure). It is given a light push so that it starts rolling with its center O moving parallel to CD in the direction shown. As it moves, the roller will tend to :