You should be able to clone the old working drive to a newer hard drive. Just make sure to clone the entire drive (and all it’s partitions). Generally the data partition is the one formatted for EX4, the other partitions generally are used to store and run the My Cloud operating system.
After cloning the old drive the new drive to the new drive, or using one of the unbrick processes on a new drive, the My Cloud Dashboard may incorrectly report the free space capacity of the new drive. If this is the case do a System Only restore from the My Cloud Dashboard > Settings > Utilities > System Factory Restore > section. If one see’s a red front LED after cloning or unbricking, attempt to access the My Cloud Dashboard anyway. If the Dashboard can be accessed, run a System Only restore to fix the front red LED issue. Basically, it is generally a good idea to perform a System Only restore at first boot after cloning or unbricking a My Cloud.
Edit to add: There is another thread that discusses using Clonzilla.
