N360 v5 Backup compatability with N360 v4 and how to Restore?

Used my N360v4 to do large Backup, moved the Backup files to another PC for safety.  Now I have to restore it after hard disk failed on original PC and had to rebuild it.  During rebuild N360 was upgraded to v5.  I can't v5 Backup-Restore to see the v4 backup files which include a large file "backup.@db" which seemed to be the index.  The layout of the v4 backup files seems to be different to what it does in v5.  Any info please?

Seems to be working now.  Backup couldnt see the set I was trying to use as it was on same drive as default set, so moved it to USB HDD and put the Arestore.exe and Arestore.loc in the root dir.  Seems to be restoring fine.