There's a rebuild utility, although the only mention of it in the docs
(we've got the DOS version 0.92) is in the Q&A section at the end. If you
run REBILD with no arguments, it'll tell you the command flags. If you look
at the mailing list archive on the web site, there's some messages in there
(subject may be size of the news database file) that also talk about
rebuild. It should, in any case, clear up your problem.
- DaveL