  We present new radio observations of the z = 0.029 radio galaxy NGC 6109, a
member of the 3CRR sample. We find the radio morphology of the counter-jet to
be highly distorted, showing a unique 'doughnut' structure ~6 kpc in diameter.
The doughnut is overpressured compared with the surrounding atmosphere as
measured with Chandra. We investigate the polarisation properties of the source
and find evidence for an interaction between the doughnut and the external
environment. This may cause the extreme jet bend. Alternatively, while
providing no explanation for the rotation-measure and magnetic field structure
seen in the doughnut, a ballistic precession model may be feasible if the
ballistic flow persists for a distance much less than the full extent of the
100 kpc-scale jet. A light jet being deflected by gas flows and winds just
outside the transition between the galaxy and cluster atmospheres appears to be
a more plausible interpretation.
