Issues with absolute/relative paths and public/private file system

Hi, I'm having issues upgrading a project that was created before my time:

Original site:
-Drupal 5.7
-Image Assist 1.4
-Private file system in Admin/Config/File System
-Absolute paths in Admin/Config/File System, so all the image URL's in database are absolute (doh!)

Upgraded site:
-Drupal 5.23
-Image Assist 1.8
-Public file system in Admin/Config/File System
-Relative paths in Admin/Config/File System, so all the image URL's in database are absolute (doh!)
-Ran a PHP script to strip the absolute path from everything in the 'files' table (1000's of files)

PROBLEM:

Old Image Assist thumbnails do not display. New images are fine though.

When clicking an old node which has an Image Assist image in the body, no image is displayed. When looking at the HTML code with firebug, no tag is there, only a span container. So obviously there's no image even being attempted to be rendered.

When going to Edit, I see the Image Assist code, including the NID for the image. When looking up that NID in the database... I see it associated with the node in the table 'img_assist_map" and the NID also exists in the 'files' table with the path to the image file. I check the path and it works in my browser, the image is there. When loading the image node directly in the browser, no image is displayed. When doing this on the old site, an image is displayed.

QUESTION:

Aside from the tables 'files' and 'img_assist_map', what other tables are involved in the regular operation of the Image Assist module? It seems like this module isn't as simple as those two tables.