If possible use a 2TB disk since this is how this procedure was tested and used so far, but if you don't have one I can modified and it still should work.
Shutdown, swap disk 13 with original disk, use a new/spare 2tb disk for disk9.
-Tools -> New Config -> Retain All -> Apply
-assign missing disks (9 and 13) -check both "parity is already valid" and "maintenance mode" before starting the array
-start the array (disk9 can show up as unmountable or with other data depending on what's there, ignore for now*)
-stop array, unassign disk9
-start array, check emulated disk 9 mounts and contents look correct
-stop array, reassign disk9
-start array to begin rebuild
*edit: this was true previously but new procedure now first starts the array in maintenance mode so there's no mounting.