The surface group representations of Euler class zero into PSL(2,R) are those which are deformations of diagonal (reducible) representation. Marche'-Wolff showed that the mapping class group acts ergodically on these representations with the strange exception of genus 2. We explore the infinitesimal data describing a deformation from a diagonal representation to an irreducible representation, and examine how the Torelli group acts on these deformations. Joint with James Farre.