I've been using deja-dup for a while. It works as long as I run it manually, but it never runs as scheduled. Right now it says "Next backup is today. A backup automatically starts every day," but the last backup was 13 days ago.

First question: does anybody have any idea how to make it work??

Assuming the answer to that is no, I've given up on getting it to run as scheduled, and I figured I would just run duplicity at the command line and schedule a cron job. Unfortunately, when I try to do an incremental backup with duplicity, I get:

I figure those old signatures must exist somewhere, but evidently not in my home directory, and I don't know where to find them.

I could just do a completely fresh duplicity backup, I'm just wondering if anyone knows where deja-dup keeps the signature files. Also wondering if it keeps the include & exclude lists anywhere that I can actually get to, because my exclude list is quite long and I'd rather not have to retype everything. I found some config files but not those lists.

Greetings,

Well, I can say that the location of the signatures should be with the backup files.
Now for the configurations, I would check if your list has been broken up into one of the XML files that it puts under "$HOME/.gconf/org/gnome/deja-dup/". From doing a quick look at those files, I would bet that it would break out each exclusion to it's own XML entry in one of the files under that directory.

HTH. Let us know.