wizard-created "events" database: how to query payments?

[Information NBM]

I use the events database created through the wizard. It does not come with a
readymade query for attendees that have not yet paid for their registrations.
I can scroll through the attendees in form view and see where it has
calculated "amount due" for each one, but can't find a way to get this
information all together in one table, query, or report to see all at once
who has a number other than zero in their "amount due" caluculation (under
registrations which appears in a box below the attendee information in the
attendee form).