I have been trying for a long time to get a Windows 7 computer current on the updates. I have just been letting it boot with failed updating since it is still usable.
But recently I have some luck getting successful installations, including some that had failed before (KB3118401, KB4539601, KB2538243). So I will try again to get the others installed.
The 3 which still consistently do not install are KB3068708 KB4503548 KB3080149.
Using the troubleshooter, two codes are generated: Code 80070490 encountered unknown error and Code 643 encountered unknown error.
All advice appreciated. At present, I am running sfc /scannow.