Hey there, Randy.
As you've mentioned it already, it could be the drive, cables or SATA port (most probably). I'd recommend that you backup any important data which you might have on that drive as soon as possible. After that go ahead and download the HDD manufacturer's diagnostics tool and test the drive for errors and bad sectors, to see if anything out of the ordinary pops-up. I'd recommend that you try the HDD with a different SATA port and cables, or even better- a different computer, to rule out a possible fault with the cables and the port.
Hope that helps. Please let me know how everything goes.
Boogieman_WD