Lee,
The issue is shown in the "nbemmcmd" output, the "Last Write Host" field is "NONE". That is the problem, it is suppose to be a Media Server name.
It looks like you have confirmed, not frozen, no images, and not in the merge table. If that it correct, and only if that is correct, use the "bptm" command to add the Master Server to the "Last Write Host", and then expire with the "bpexpdate" command.
On the Master Server
cd /usr/openv/netbackup/bin
./bptm -makedbentry -m NH1007 -den hcart3 -poolnum 2
cd /usr/openv/netbackup/bin/admincmd
./nbemmcmd -listmedia -mediaid NH1007
(The Last Write Host field should be filled in)
./bpexpdate -m NH1007 -d 0 -force
That will do it.