grsync not deleting files

[rikona]

Changed disks recently. Using 2 different disks for storage and
backups - a USB to back up a local non-boot disk - all disks ext4.
Both disks have a 'lost+found' folder, root permissions. Ubuntu 12.04.
Properties for both disks say 'some contents unreadable'. I'm assuming
that's because of the 'lost+found' folder, but please tell me if
there's more to it...

In grsync, I have 'delete on destination' checked. When I backup the
local disk to USB, it does copy newer files, but does not delete older
files. At the start of the progress window it says 'permission denied'
for the 'lost+found' folder. Next line: 'IO error - skipping file
deletion'. And indeed it does no deletions for any file.

How can I get it to delete files that are no longer on the
source/local disk?

Also, I recently copied the old local disk [1G] to the new 2G local
disk mentioned above - I was running out of space. Is it possible that
this copy did NOT copy all the files? I just assumed it would and
didn't check.

-- 
Thanks,
 rikona