Thank you for your reply to my assistance request.
Two points:
1. On Tuesday (22 Mar) the system did successfully download and install some updates, namely: KB890830, KB3144756, KB3140741, KB3140768. Then yesterday it failed to install KB3140743 and KB3139907 once again (third time).
2. Although I do own a Dell machine with NVIDIA drivers installed, this topic refers to my ThinkPad X1 Carbon, which has no dedicated graphics card. Plus, DISM still returns error 0x800f081f.
If this is normal, then I apologize for wasting your time.
Tim