Changing permissions broke colorbox

I upgraded a copy of a site to the latest releases of Drupal and modules. I had a problem that my web host said was a permissions problem, and he tweaked them and all worked. To be sure all was as I thought it was, I re-did my copy and got it working again. This included replacing colorbox with the latest version. To be sure all permissions were set properly, I ran

find -type d -exec chmod 755 {} \; at the top level of the site copy, then

find -type f -exec chmod 644 {} \;

and all directories were 755 and all files were 644.

But now, Colorbox doesn't load and I see only the image nodes. Isn't this as the file permissions are expected? What can I do to get it working again?