  Many service systems provide customers with information about the system so
that customers can make an informed decision about whether to join or not. Many
of these systems provide information in the form of an update. Thus, the
information about the system is updated periodically in increments of size
$\Delta$. It is known that these updates can cause oscillations in the
resulting dynamics. However, it is an open problem to explicitly characterize
the size of these oscillations when they occur. In this paper, we solve this
open problem and show how to exactly calculate the amplitude of these
oscillations via a fixed point equation. We also calculate closed form
approximations via Taylor expansions of the fixed point equation and show that
these approximations are very accurate, especially when $\Delta$ is large. Our
analysis provides new insight for systems that use updates as a way of
disseminating information to customers.
