How can I tell CWM to perform a full backup instead of an incremental backup? A recent update to CWM touted the ability to perform incremental backups instead of full ones.  Having performed those for a while, I find that I have quite a few old backups that I don't know if I can remove, since newer backups may depend on them.

Last time I was in this situation I deleted all of the backups and made one full clean backup.  That, however, carries the risk of some failure before the new backup is complete.  Is there any way to tell CWM to perform a full backup, so that I can safely remove all of the old ones?
Technically, CWM 6 isn't doing incremental or full backups. What it is doing is storing "blobs" that are shared between backups if the data hasn't changed between the two. When you run a new backup, it reuses what it can. If you delete a backup set, you don't actually delete the data, and the next time you run a backup, CWM deletes any blobs no longer in use.