RR, thanks for the reply. That's reassuring (sort of)
The problem came to light because I was testing the new Notamplot filter at
http://mysite.freeserve.com/ais2plot/index.html experiencing the joy of using Notamplot again when some of the Notams seemed familiar.
So far as I can see, the 'one touch' area and the narrow route briefing work OK.