Downloaded full version using latest Windows Media Creation Tool.
Updated everything I can think of and can find on my Surface.
Checked system files with sfc /scannow.
Update to 1607 fails with error:
0x80070002 - 0x20007
"The installation failed in the SAFE_OS phase with an error during INSTALL_DRIVERS operation."
Reverts to 1511 build. All suggestions welcomed. I have upgraded three other Win 10 computers today without problems using same downloaded file.