Faces not appearing on cork board

I'm running OS X 10.9.5 and iPhoto 9.5.1. I recently had a hard drive crash and replaced my hard drive and restored it from a time machine backup. Now many of the thumbnails in the cork board in the Faces portion of iPhoto no longer appear, making determination of who is the picture actually of very, very difficulty. I've rebuilt the thumbnails, repaired the permissions, repaired the database, and rebuilt the database, but the problem persists. Is there any way to restore the thumbnails in the cork board of the Faces portion of iPhoto?

I saw this old discussion from 2009 https://discussions.apple.com/thread/1888068?start=15&tstart=0 which suggests deleting the face.db file in the iPhoto database, but I can't find that file in the iPhoto database--it may only exist in version 8 of iPhoto.