I should have said that it was a desktop PC and not a laptop.

Backing up is just about complete. I will then boot into W7 and try making
recovery disks. There is nothing on W7 so I do not need to do a restore. I
have everything important on my home partition which is backed up three
times now. Some files are backed up on an external drive. Some are backed
up using Deja Dup, but it is encrypted so not much use until I need to
restore from it. It was my insurance if things went quickly. Now my entire
home and Windows userspace is backed up on another external drive.

I have bought another drive to replace the dying Seagate. I will try
cloning first. If that does not work then I will try re-installing from
disks and then copying userspace back from my backups. It takes a long time
to copy tens of thousands of files. :(

I may be on my tablet for some time and will let you know how it turns out.