How to service builders?

As an example, currently the builder status says xenbuilder2.fedora.redhat.com (unavailable) but xenbuilder2 ~]$ /sbin/service plague-builder status plague-builder (pid 1939) is running... so assuming I wanted to restart it as a simple first step, where do I find the documentation? Basically, I would be interested in whether it requires root privileges and what role the account system groups play (if any).