I/O error on WD Elements 3TB

I have had a WD Elements 3TB external hard drive (#WDBAAU0030HBK-01) for less than a year.  Last night I was transferring a large folder from my laptop PC to the external drive.  The transfer stopped in the middle because of an I/O error and I could no longer access any files on the external or safely remove it.  I then shut down the PC and disconnected the power cord from the external and rebooted both.  I could access the external again, so I tried to transfer the remainder of the files.  The same exact thing happened mid-transfer.

I then went to the WD website and downloaded the diagnostic tool WinDlg.  The SMART test said that the external drive was in failure because the re-allocated sector count was reading at a 133 value when the threshold should be 140.

So far I have been able to back up the files with no trouble (transferring from the external to the PC).  The trouble doesn’t seem to start until I try to copy files back onto the external.  It seems like I can take stuff off the drive, but not put stuff on it.

Is this a driver problem or is the external likely facing mechanical failure?  Any help would be greatly appreciated.

SMART failure requires to replace the drive

Good thing you were capable of backing up your files