Ah fantastic thank you both, problem is now solved.
Yes there was a link missing in the chain of folders. Although I did have the CONTENTS folder, I did not have the CLIPS001 folder.
I didn’t see the wood for the trees! Even though I spent ages looking at those that worked and those that didn’t to to compare and check that all Journal Folders, Index files, .CIF, .XML were all present and accounted for, I MISSED the fact that a folder was missing in the middle.
Thanks again.