hi.. there are two ways to do this.
1. in a url, type
http://Ip_address/sec_cont/ops/taskstatus.htm. Go to the bottom of the page and you will see your savecores by date. You can then click on download to copy them over.
2. If you ftp into the nbx using the administrator username and password, the cd /htfs0.
You will see a folder there named
Core_mmmdd_mm_ss. The folder is named by the date and time you did the savecore. Just go into that folder and pull of the .tar file.