Problems with external MyBook Essential 250GB

Hello all, first time on this Forum.

My MyBook Essential is around 3 years old.
Model Number  WD 2500JB External
Serial Number WD-WCANK8145909

There are some bad sectors and tried to fix them with WD Data LifeGuard Diagnostic.

I tried check disk and failed.
Report is:

Quick Test on drive 3 did not complete!
Status code= 07 (Failed read test element), Failure Checkpoint = 65 (Error log Test)
SMART self test did not complete on drive 3!

First I like to know what’s the meaning of that report.

Is this supposed to be a board or a disk failure?
If the disk is bad may I replace it with another WD drive?  Which one?

Any help will be apprteciated.

Thanks