Library is now complete (https://discussions.apple.com/thread/3646104), however, some albums were missing Artwork. Working on my Laptop library all Artwork is now complete. Following an 'Update iTunes Match' prompt the majority of the Artwork has migrated to all other libraries but not all. How can this be corrected?
1. On laptop, select all music view in grid form;
2. For each missing Album Artwork;
(a) Find Artwork using Google images;
(b) Save a local copy;
(c) 'Get Info' for Album in Grid view;
(d) Paste correct Artwork into appropriate box;
(e) Confirm Artwork update.
3. On completion, select 'Update iTunes Match' from menu;
4. Start alternate computer with iTunes Library using iTunes Match;
5. Select 'Update iTunes Match' from menu;
6. Use Smart List to track Songs without Album Artwork.
All Artwork complete, with some exceptions, not sure why these exceptions exist ... please help ...
Many thanks in anticipation
After much searching have found the answers buried in another forum (http://cybernetnews.com/cybernotes-add-album-art-in-itunes/).
iTunes Match does not presently reliably replicate Album Artwork across libraries - it does however make impressive if partial progress hence still worthwhile.
Method outlined is correct - it is best to use the Library All Songs Diplayed by Album Grid format - Get Info here presents a single Artwork location for all associated tracks.
Using a Smart List on each library to track apparently missing Artwork works well.
Saving the Artwork retrieved from Google at 300 by 300 72dpi to a shared folder works well.
Having completed an initial library - worth Get Album Artwork request, ahead of Update iTunes Match request.
In each target library repeat the Get Album Artwork and Update iTunes Match request.
Working from the Smart List for No Artwork, sort by Album, use shift-click to select all tracks for each Album, Get Info, paste in Album Artwork from shared folder.
Once complete - for each subsequent library complete a Get Album Artwork and iTunes Match request.
Confirm that both all entries in Library All Songs Grid View are complete and that the Smart List for No Artwork is empty.
Repeat for each library in question - it really is very fast.
Whilst it is frustrating the iTunes Match does not manage this automatically, once complete each Library is a pleasure to use allowing all Songs to be navigated via Album Artwork.
Good luck - the finished result really is worth the small amount of effort involved!