So, we have a far from ideal situation.

Right now I'm restoring the new drive back to Jan 2014, the time before last that it backed up before upgrading to Mavericks. Hopefully that will work acceptably. I can recover nearly all my data from the repositories I created before migrating, the exceptions being latest info from Firefox and the emails received in the last 2 months.

I'm not sure yet how to tackle the emails - really don't want to lose some of them - but I'll probably try the archiving again. I may also see if there's a more rudimentary, yet simpler way to save them.

And I'm becoming increasingly sympathetic toward replacing this computer. Presently typing from the little Philips Freevents I bought last year. In the end Mint Debian was removed, because it's relatively slow and clunky compared to Linux Lite, and I've returned to that.