Thank you Susan, and thanks to Apoorva Shukla from Microsoft, who successfully installed KB2862330 for me. It took well over an hour because of scans, for troubleshooting programs needed and for data collection, but he was very knowledgeable and patient.
I unplugged USB devices, he disabled USB Host Controllers in Device Manager, and when he could not otherwise stop all Avast antivirus services, uninstalled that program to allow uninterrupted installation. Helping by remote control, Apoorva ran fsc /scannow
and downloaded, installed and ran a program helping to troubleshoot readiness to install Windows Updates.
Apoorva did check whether an earlier update needed as a pre-condition had been installed. This update was mentioned, I think, in the forum concerning KB2862330 that ran last year. Susan - for the benefit of people trying to help themselves - was that update
KB2533552, KB2525325 or KB2532531? (I think it was the first).
Log files and a CBS text document were forwarded from my computer. I wonder what that text document is?
Anyway, this experience confirms the need to disable USB - though Apoorva kept the Microsoft USB mouse and keyboard enabled. A report was to be analyzed by Microsoft - so I hope that this allows M/S to rectify the update problem!
The "ANSWER" at the head of this forum is misleading, because it implies that people can safely install version 2 of the update without any special preparations. The update still needs to be rectified.
Thank you Susan and Apoorva for your help.
Phil