Windows Update Troubleshooter is a handy tool from Microsoft which diagnoses and fixes issues with Windows Updates. If you’ve come across an update which keeps failing to install, give this tool a go. I’ve used it successfully on one of my PCs that is running Windows 8.1.
If you just want to scan for problems instead of automatically fixing them, go to advanced options (link found on first screen), and deselect “Apply repairs automatically”.
Windows Update Troubleshooter is free, and you can download it directly from Microsoft.