So I'm in the apple store in Covent Garden again with my poorly iPod classic which won't restore, just gives a nasty disk error.
"Oh that's an unrecoverable disc error - we wouldn't replace the disc, but we would sell you a new one at a discount"
"Ok" I said "I'll just go back to what I've been doing all along."
For about the fourth time in as many years, I de-installed latest version of Itunes, installed an early version (v10, which by now I have handy for this purpose) and the unrecoverable Ipod restored fine. Then I updated iTunes to the current version.
Basically the later versions of ITunes don't carry the firmware to fix the earlier Ipod classics. Errors don't indicate that of course - they just subtly suggest the iPod is dead.
This time I've renamed it "zPod"
PS : At least twice I re-seated the disc on on an old 4th generation IPod by wacking the corner on a table