Qfinder is acting up again.

Rebooted my server and QuickFinder was working. Today I tried to use it and
found the service unavailable. Going to the qfinder admin page returns
"Service Unavailable: the server is temporarily unable to service your
request ..."

A look at the console screen on the server shows that Qfinder is not
processing any index jobs (unlike last time when it was stuck in an indexing

I'm assuming that I've got a dodgy index file that's mucking things up.

What is the procedure for shutting down qfinder and restarting it?