Doug

You will want to deactivate your license on your old system to move the key to your new system when ready.  As you will initially install trial version.
If you forget then you have to submit a ticket requesting deactivate license.

You may need to do this: 
https://wiki.covecube.com/StableBit_DrivePool_Q2150495

I believe I figured it out....seems Scanner marked a single block as bad, and since I had the option for DrivePool to allow Scanner to evacuate on any issue, it did so.   I'm going to add a 3rd drive to the pool, but for now I have disabled the scanner option to evacuate, the drive is healthy except for that 1 block, but will be ready for when it craps out entirely (and I have backups).

Ah that's a tough one. If the disks SMART readings are ok then my first guess would be the JBOD chassis power supply or other hardware failing. Disk failures are usually more slow moving in that you start to see errors and corruption and will get some warning from the pool. If it completely fails suddenly then a restart wouldn't bring it back.

Wow, nice digging! 
And sorry for not getting back here sooner! 
Also, for the permissions, this should work too:
http://wiki.covecube.com/StableBit_DrivePool_Q5510455

I tried to buy my Amazon renewed drives from the seller GoHardDrive. I have purchased drives from GoHardDrive for years and their customer support has always been first rate. I feel confident they would back their warranty.

It depends on the OS
Win10 will work but say 2012r2 will not
or thats how it works for me with my 950 Pro's - unless 960's work differently

This is an issue with the Windows Home server installer.... It fails to roll back properly when there is an issue (at least in the dashboard).
 
Please uninstall the Add-In, and then reinstall it. This will ensure you're on the proper version (you're stuck on 2.4 right now).
If needed, uninstall it from the control panel first, then uninstall it from the Add-Ins section in the dashboard.

Since Drivepool becomes read only when you have a missing disk I don't believe you can add a new disk like you want to.
 
But you can still stop drivepool service and swop in your new 2TB drive (if new initialize and format via windows) and copy the content of the poolpart.xxxxxxxxxxx folder on 500GB to the new drive.  Shutdown server remove new drive readd old, start server then force remove 500GB drive (might be able to just remove 500GB drive and leave new 2TB when reinstalling old 2TB drive and just remove missing disk from dashboard).  Then add new 2TB disk. Move content into new poolpart.xxxxxxxxxxxxxxxxxxx on new 2TB.
 
DP really has nothing to do with a copy from disk to disk in this situation.  Just ensure the service is not running during this process.

Specifications:
Speed: SATA 3 (6.0Gb/s) Ports: 6x Internal Mini SAS SFF-8087 Slot: PCI-Express 2.0 x16 Chipset: See Marvell 9485 SAS/SATA Controller Chip Firmware
Firmware: 1.3AHCI compatible: No (proprietary driver required) Link: http://www.highpoint-tech.com/USA_new/CS-PCI-E_2_0_x16_Configuration.html Driver: 1.2.12.1023 (10/23/2012)rr276x.sys Link: http://www.highpoint-tech.com/USA_new/CS-PCI-E_2_0_x16_Configuration.html Performance
SATA III SSDBurst: 481 MB/s Drive: Intel SSDSC2CT180A4 OS Tested: Windows Home Server 2011
  SATA II HDDBurst: 171 MB/s Drive: Seagate ST3200045AS OS Tested: Windows Home Server 2011
SATA III HDDBurst: 459 MB/s Drive: Seagate ST2000DM001 OS Tested: Windows Home Server 2011

I have a Norco 4224v1 4U case.
 
CPU: Intel i3-530
MoBo: HP ProLiant ML110 G6
RAM: 4x2GB CORSAIR Vengeance
GFX: Onboard
OS Drive: 180GB SSD, Intel 335 Series (WHS 2011)
Storage Pool: 13x2TB (Seagate ST2000DM001)
HDD Controller card: HighPoint RocketRAID 2760 (All drives connected to controller)
3TB Seagate ST3000DM001 for Server Backup (system drive, and system files) / Client Backups
Drivepool / Scanner