  Several multi-frequency polarization studies have shown the presence of
systematic Faraday Rotation gradients across the parsec-scale jets of Active
Galactic Nuclei (AGN), taken to be due to the systematic variation of the
line-of-sight component of a helical magnetic field across the jet. Other
studies have confirmed the presence and sense of these gradients in several
sources, thus providing evidence that these gradients persist over time and
over large distances from the core. However, we find surprising new evidence
for a reversal in the direction of the Faraday Rotation gradient across the jet
of 1803+784, for which multi-wavelength polarization observations are available
at four epochs. At all four epochs, we observe transverse Rotation Measure (RM)
gradients across the jet, consistent with the presence of a helical magnetic
field wrapped around the jet. However, we also observe a ''flip'' in the
direction of the gradient between June 2000 and August 2002. Although the
origins of this phenomena are not understood, one way to interpret this change
is if the sense of rotation of the central supermassive black hole and
accretion disc has remained the same, but the dominant magnetic pole facing the
Earth has changed from North to South.
