Hi there bostonjl,
That is really unpleasant.
Externals could make clicking sounds due to the following reasons:
- Not enough power supplied to the drive. You can attach it with a different cable to another SATA port or even computer.
- Some physical failure.
If the issue persists after attaching the drive with a different cable, then you can either RMA the product, or contact a data recovery company if the data stored over there is really important.
Cheers,
D_Know_WD