This paper studies the classical polling model under the exhaustive-se
rvice assumption; such models continue to be very useful in performanc
e studies of computer/communication systems. The analysis here extends
earlier work of the authors to the general case of nonzero switchover
times. It shows that, under the standard heavy-traffic scaling, the t
otal unfinished work in the system tends to a Bessel-type diffusion in
the heavy-traffic limit. It verifies in addition that, with this chan
ge in the limiting unfinished-work process, the averaging principle es
tablished earlier by the authors carries over to the general model.