Hi James
I've copied a replacement library file in off another MBP and that seems to have done the trick.
For the record, neither SuperDuper nor Time Machine reported a problem with their backups, but your software reported it. When I checked back through the system logs I found errors for both of those dealing with the same file.
In other words, I am really pleased that QRecall flagged an error onscreen.
Cheers
Nik