Kirby, Thanks - I can't upgrade to 3.3.1 because according to the download page http://support.apple.com/kb/DL1553 that version required OS X 10.7.4 or later. I have OS X 10.6.8 and my version of Aperture is 3.1.2 which I think is as up to date as I can get on that version of OSX. The last time I checked for software updates nothing was download for Aperture as I recall, a couple of months ago.
I can't update that computer (a Mac Mini) again at the moment because it doesn't have internet access. It is installed on a boat, in a marina in deepest darkest Uruguay. I can only get internet access by lugging a laptop (windows) somewhere. I certainly can't upgrade to OS X Lion.
Anyway I tried to follow your instructions with what I have and these are the dialogues that I received.
I created the new library
Then did File - Vault - Restore Library ( note that Restore vault is not an option)
I choose to restore the library
I then get the error message
"Photos 1 backup" was created by an older version of Aperture, and can not be restored by this version.
To import the contents of the vault,select the import button
I click import, and receive this error message
Library import error
The library connot be imported because some the data required for import could not be found
The file is on a hard drive which according to the info is "Mac OS extended (journaled)"
Hmmmm just noticed that if I get the info for the vault file it shows as only 4k... is that just showing the folder size or is the vault empty?