This worked for me. I'm thinking that the automated process fails NOT when there is insufficent disk space, but when File System Services sends the warning that disk space is low. I had 71GB free, but also had the low disk space warning in the filesystem.
Also, thank you for indicating where these files were. I had attempted the automatic process several times... I had quite a few 7GB DMGs in this folder, all identical, but with different UUIDs.