I am running Windows 10 on the Surface Pro 3. I would like to check the health of the hard disk, because some WinSxS files have become corrupted. How does one do this?
Check the Windows Event Log for disk errors.
This is something you can do with stock Windows software, no add-ons. And the data has already been logged on your PC. ie this isn't a test you have to start running now; you can look for problems that occurred in the past.
Open Computer Management (run compmgmt.msc) and in the left pane, nav to System Tools | Event Viewer | Windows Logs , click System. In the right pane, click Filter Current Log. In the Event Sources selector, select "disk" and "Disk". OK. Your middle pane should now show all disk-related events.
If there aren't any "warning" or "error" level, you're good. :) You may be good even if there are a few, depending on what they are. If the text shows anything about "retries", though, that's bad.