  We have observed a new, complete, cooling-core sample with the VLA, in order
to understand how the massive black hole in the central galaxy interacts with
the local cluster plasma. We find that every cooling core is currently being
energized by an active radio jet, which has probably been destabilized by its
interaction with the cooling core. We argue that current models of cooling-core
radio galaxies need to be improved before they can be used to determine the
rate at which the jet is heating the cooling core. We also argue that the
extended radio haloes we see in many cooling-core clusters need extended, in
situ re-energization, which cannot be supplied solely by the central galaxy.
