Need to clone failing secondary (media only) HDD to new drive. What software?

There is an easy and free way to do this, since you are working with a desktop machine running Windows.

Since your NEW HDD is from WD, go tho their website and download their free utility package called Acronis True Image WD Edition. Install it on your existing C: drive. One of its many tools is cloning, just what you need. ALSO get the manual file and READ it! There are a couple of items you'll need to understand.

First, a size issue. To use ALL of a 3 TB HDD in one large Partition you MUST use a GPT Partitioning system, not the older MBR system. (MBR is limited to 2 TB as its max drive size.) To do that, you MUST be using a 64-bit version of Windows 7 or above. Microsoft only provides a driver for GPT-Partitioned drives with its 64-bit versions. If you are planning to stay with a 32-bit version already installed on your C: drive, check with WD for help in getting around this driver and size issue.

Check also with WD Tech Support for how their cloning utility can clone an MBR older drive to a larger GPT drive.

Connecting both your new and older drives should not be too hard IF your motherboard has an unused SATA port on it. You do not have to physically mount the new drive in your case to do the cloning operation, which will only take a few hours at most. You can simply place the new drive on some insulating surface like a plastic sheet or dry board, as long as you can get it close enough to connect the power and data cables to that drive. AFTER the cloning is complete you can swap things around to permanent placement. Even if you don't have an unused SATA port, sometimes you can temporarily disconnect an optical drive and use that port.

Cloning makes a complete copy of everything from Source to Destination units, but you need to make some adjustments via the utility's menu system when (as is your case) the two drives are of different sizes. There are two possible scenarios here.

The simpler situation occurs if the Source unit has only one Partition on it. The common default set of parameters for many cloners seems to be to make the new Partition on the Destination unit the SAME size as the old one, which you do NOT want! So, when it asks you to confirm its proposed settings and let it proceed, do NOT approve! Use the menus to change the size of the new Partition on the Destination unit to the full space of the new HDD. Per WD's advice, ensure that the new unit will be set up under GPT Partitioning. Since this is a data-only HDD, it does NOT need to be Bootable. Most other default settings will be OK. When you have it all set up right, then tell it to go ahead. It will take a lot of time, so be patient.

The second scenario is when your Source unit has more than one Partition on it. The common default plan seems to be "Proportional Partitions". In this scheme the sizes of the proposed new Partitions on the larger HDD will be in proportion to those of the older unit. In your case, going from 2 TB to 3 TB, it would propose to make every new Partition 1.5 times the size of the originals. But some of those (for example, a System Reserved Partition) do NOT need to be any larger than they are because there will never be any new data added to them. So again, use the menus to specify the proper sizes of new Partitions on the larger 3 TB unit, and let your data storage Partition get all the space it can.

I cloned a failing unit a couple of years ago, and had an issue: the operation kept stopping to tell me that it had an error reading particular Sectors from the Source unit. I kept telling it to go ahead anyway, but that got boring and kept me there. So ultimately I told it to ignore all such problems and just keep on cloning it all. The risk I took is that the Destination (new) disk could have data written to a few files that contains erroneous data because the original could not be read correctly. BUT there's a good chance those read errors actually were on Sectors of the old drive that were NOT involved in any data file, so the errors don't matter. That's the "bet" I took, and I have never found a problem with erroneous files on the cloned new disk.

When you have finished, shut down your machine. Disconnect the old HDD and remove it. Mount the new one in the case and connect its data cable to the SAME mobo SATA connector the old one was on. That should help Windows figure out where the new drive is.