Access backup files

I have a Maxtor external hard drive that I use only for periodic backups. Well, during my last auto-scheduled backup it failed. So I went in to do it manually and I get an error message stating an 'inconsistency in the backup..." I did a bit of research and something said to do a defrag of the drive...so I went to do that and found the drive is Full - 0% free space. It's strange because my settings are to append the previous backups - but either way, I have no problems with my computer and would be willing to delete all current backups entirely, and do a fresh backup, but can't seem to actually access the contents of the drive.

When I explore the drive I only get the backup utility and one 1kb file named DO NOT DELETE.media or something like that. How do I get into the actual files to move them or delete them?