the internal mechanism came out of alignment. . it is one of the major problems of the maru. pull open the centers on all sides and you will see that you cannot see the 'screwheads'. split apart the edges and you'll probably find it there. then, just find which side (r or l) moves the screw around. which ever side moves the screw, grip that side very tightly and try to move it back inbetween the centers. . .