On a single workstation, I want to uninstall Symantec Endpoint Protection 12.1.4. However, I always get a fatal error on uninstall.

I checked the Windows Application Event Log, and it shows the following error:

Faulting application name: installTeefer.exe, version: 12.1.4013.4013, time stamp: 0x5264804d
Faulting module name: nvd3d9wrapx.dll, version: 10.18.13.5330, time stamp: 0x558103e5
Exception code: 0xc0000005

I remember manually installing the teefer driver to each of the network devices on the workstation, but they seem to have disappeared completely (hence, I want the fresh install). 

What would be a logical next step? The manual uninstall procedure fails as well, since I can't find the registry keys associated with Teefer.

Please try cleanwipe, see this article for full direction:

http://www.symantec.com/docs/HOWTO74877

I tried it, but it didn't work. The default Symantec uninstaller ran by CleanWipe crashed on the `teefer` uninstaller. How can I specifically remove (or install it correctly so the installer knows how to properly remove it) Teefer?

Please follow the Manual removal procedure for Teefer driver according to your O/S & Version fromt he below article.

How to manually uninstall Symantec Endpoint Protection 12.1

Have you followed the manual removal guide found here?

http://www.symantec.com/docs/TECH179644

Just make sure running the latest version of Clewanipe, if Cleanwipe also failed then need to perform manual removal guide.