It worked Dan. So thanks for that. Incidentally, I didn't force the debug options on as described in steps in this thread so took a bit of a chance, and it still worked.
It took several reboots before all the configuration items appeared on the Web config page. Not sure why. Also, it appears that my unit goes into a unusable state depending (perhaps randomly) on the Power save timer options. Oh well...
But good to get it working again.