Problems Restoring from Backups

[AndrewB]

My SD card (Sheeva) died as a consequence of a power outage (failed to boot).
I got a replacement card, loaded a fresh image (4.9 Build 929), transferred my licence, reconfigured all my sensors and everything appeared to be fine. New data being collected, graphs drawn and uploaded, etc.
But... Now that I come to try and restore my weather data, I find that I can't.
I've been backing up, as per the manual, by mapping to /public from my windows PC and just copying all the files across.
I had expected to restore the data in the reverse manner. I am able to map to /public and it seems as if the first couple of months data transfers but then I start getting messages from Windows about "needing permission". After this, the meteohub gui typically shows "error file open /home/meteohub/meteohub.conf" and nothing seems to work anymore.
If I force a reboot, meteohub appears to wake up normally, with no error message, but there is no trace of the restored data.
Thinking it might, literally, be a file ownership issue, I tried doing it the other way round. I placed the backup raw files on an FTP server, SSH'd into meteohub (as root) and used wget to pull the files onto meteohub. This appeared happier, in so far as I was able to see that the files had indeed been copied to /data/.... but not long after that meteohub hung up again, same "error file open" message.
Reboot again, appears to be back to normal, but restored data has vanished.

So, what do I try next? Suggestions anyone?
Is this even the correct way to be trying to restore weather data?

Regards,