Unfortunately, I was hoping I would never have this problem again, but I'm once again having this problem. The "Recover RAID Array" button is clickable, I click on it, click Yes to continue, I enter the 4 digit code, and then it fails with "A system error occured. Reboot the LinkStation and try configuring it again." Same thing as I had reported before. I restart the LinkStation and try again. Same problem. I still have the failed drive, so I might try re-installing it, check the array, and then try the new drive again. I've found that when I format the new drive that then I can never recover the array, but I didn't do the process RudyNAS outlined. I have to "unformat" it in order to use the recover button.
I tried Texturtle's link (which is what is in the manual) and Step 18 (the last step) is what does NOT happen. Same as what happened to me before.