Replacement Drives for 12 TB G-RAID w/Thunderbolt 2?

I cannot seem to locate where I can purchase replacement drives. The 12 TB rocks but the drives are making noise and I want to get new drives, back up the media and reformat the original drives to see if that corrects the issue.

I also have an 8 TB G-RAID drive.

HERE is a direct link to the 8TB spare drive replacements. From that link you can also click the other capacities if you wish to pick another.