  We present spin-resolved X-ray data of the neutron star binary Her X-1 taken
using the EPIC detectors on XMM-Newton. The data were taken at three distinct
epochs through the 35 day precession period. The energy dependent light curves
of this source vary significantly from epoch to epoch. It is known that the
relative phasing of the soft (<1 keV) and hard (>2 keV) X-rays varies. Here, we
find that the phase shift between the soft and hard bands during the main-on
state is considerably different from that observed in the past. Further, it
continues to change significantly during the other two observations. This
suggests that we are observing, for the first time, a it substantial and
continuous variation in the tilt of the disk, as it is expected if the
accretion disk is precessing in the system. Analysis of the spin resolved data
confirms that the equivalent width variation of the fluorescence Fe K line at
\~6.4 keV follows that of the soft X-ray emission in the main-on state, thus
suggesting a common origin for Fe K line and thermal component. The Fe K line
is considerably broader when the source is brightest.
