Do not do "new catalog and re-import".
In the Folders panel, right click folders (start at top level) and Update Folder Location. Continue until no question marks on folders.
Then run Library > Find Missing Photos. If any are still missing, go back over the folders and repeat above. If still some missing, go to grid view and click the question mark on the thumbnail.
Thank you very much
I knew there had to be a different way... (8^))