  We present the results of modeling 5, 8 and 15 GHz maps of the gravitational
lens MG1131+0456 using the LensClean algorithm. Two models for the mass
distribution in the lens were fit: a de Vaucouleurs model and a model with the
two-dimensional potential phi = b^{2-alpha}(r^2+s^2)^{alpha/2}/2alpha, both in
an external shear field. The best fit de Vaucouleurs model has an effective
radius of R_e = 0.83+-0.13 arcseconds, larger than that measured at optical
wavelengths. The best fit ``alpha model'' has alpha=0.6+-0.2 and a core radius
of s = 0.19 +- 0.07 arcseconds. An isothermal model (alpha=1) is inconsistent
with the data. The best alpha model fits the 8 GHz map significantly better
than the best de Vaucouleurs model. Although it is difficult to distinguish
visually the original image and the reconstructions, none of the models is
statistically consistent with the data. We believe the primary problem is that
an external shear is an inadequate model for the angular structure of the lens
galaxy. The finite core radius in the models is required by the structure of
the extended ring, so we confirm that the central component in the 8 GHz map is
a central, lensed image of the source rather than the lens galaxy. The model
lens positions, the position angle of the shear, and the mass interior to the
ring are determined very precisely by the lens models. The time delay between
the compact components is predicted with an uncertainty we estimate to be at
most +- 9%; the formal uncertainty is +- 4%.
