  We apply elliptical isothermal mass models to reproduce the point source
properties, i.e. image positions, flux density ratios and time delay ratios, of
the quadruple lens B1608+656. A wide set of suitable solutions is found,
showing that models that only fit the properties of point sources are
under-constrained and can lead to a large uncertainty in the prediction of Ho.
We present two examples of models predicting Ho=100 km/(s Mpc) (chi^2=4) and
Ho=69 km/(s Mpc) (chi^2=24).
