I extracted system.management.automation.dll from the install dvd using 7-zip.
This was in the Sources\Windows\winsxs\(written out just below) folder.
I took ownership of C:\Windows\winsxs\msil_system.management.automation_31bf3856ad364e35_6.1.7601.17514_none_236c706c3e9 3d144.
Right-click that folder-Properties-Security-Advanced-Owner-Edit-pick Administrators; check off "Replace owner on ...." and OK out.
Right-click again-Properties-Security-Edit. Select Administrators and check Full Control then OK out. Delete the corrupt dll in that folder and copy the newly extracted one.
Now you have to give ownership back to TrustedInstaller.
Right-click that very long-named folder-Properties-Security-Edit. Here you change Administrators permissions back to Read & Execute, List, and Read; OK out.
Right-click again-Properties-Security-Advanced-Owner-Edit. Go into "Other users or groups" and type in NT Service\TrustedInstaller to add its' name back to the list. OK once. Here you select TrustedInstaller and check off "Replace owner ....." and OK out.
I ran sfc /scannow once in an elevated prompt. It still found that dll to be a problem, but I think a repair was pending upon a reboot. I restarted.
Then, using the DART 7.0 bootable multi-utility disc (an IT favorite) I performed an sfc /scannow offline after another restart. I was rewarded with no integrity problems. The Windows Power Shell on this pc is clean.
Huge thanks to Brink for his tutorials on extractions & permissions giving me the procedures for all this work.