Windows 7 Service Pack 1 (KB976932) fails to install

Both SFC and CheckSUR results show no errors.
However, the CBS background shows the following errors...

Code:

2015-07-18 10:41:12, Info                  CBS    Exec: Resolving Package: Microsoft-Windows-Branding-Ultimate-Client-Package~31bf3856ad364e35~x86~en-US~6.1.7601.17514, Update: BUC Namespace, PinDeployment: x86_microsoft-windows-b..oyment-languagepack_31bf3856ad364e35_6.1.7600.16385_en-us_73ab661146e7ca7a
2015-07-18 10:41:12, Error                 CSI    000001bb@2015/7/18:14:41:12.904 (F) d:\win7sp1_gdr\base\wcp\componentstore\csd_locking.cpp(324): Error STATUS_SXS_ASSEMBLY_MISSING originated in function CCSDirectTransaction::LockComponent expression: (null)
[gle=0x80004005]
2015-07-18 10:41:16, Error                 CSI    000001bc (F) STATUS_SXS_ASSEMBLY_MISSING #579822# from CCSDirectTransaction::OperateEnding at index 0 of 1 operations, disposition 2[gle=0xd015000c]
2015-07-18 10:41:16, Error                 CSI    000001bd (F) HRESULT_FROM_WIN32(ERROR_SXS_ASSEMBLY_MISSING) #579707# from Windows::ServicingAPI::CCSITransaction::ICSITransaction_PinDeployment(Flags = 0, a = Microsoft-Windows-Branding-Ultimate-Deployment-LanguagePack, Version = 6.1.7600.16385, pA = PROCESSOR_ARCHITECTURE_INTEL (0), Culture = [l:10{5}]"en-US", VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral, cb = (null), s = (null), rid = [106]"Microsoft-Windows-Branding-Ultimate-Client-Package~31bf3856ad364e35~x86~en-US~6.1.7601.17514.BUC Namespace", rah = (null), manpath = (null), catpath = (null), ed = 0, disp = 0)[gle=0x80073701]
2015-07-18 10:41:16, Info                  CBS    Failed to pin deployment while resolving Update: BUC Namespace from file: (null) [HRESULT = 0x80073701 - ERROR_SXS_ASSEMBLY_MISSING]

I'll have to do some research and come back to you.

With luck, this will fix the problem...
I've uploaded a file - ubkaa.zip - to my OneDrive at Noel's OneDrive
Please download and save it.

Right-click on the saved file and select Extract all...
Change the target to C:\ and click on Extract
Close all windows (it would be a good idea to print these instructions!)

Now reboot to the Repair Environment - as soon as the machine restarts, start tapping F8 - this should bring up the Advanced Boot Menu, at the top of which should be the option 'Repair my Computer'
Pick that
You'll have to log in with your username and password.

Pick the option to use a Command Prompt
At the prompt type
DIR C:\ubkaa
hit the enter key - if you get a 'Not Found' error try
DIR D:\ubkaa
or
DIR E:\ubkaa

The drive letter in use when you find the folder will need to be substituted (for<drive>) into the following command...

XCOPY <drive>:\ubkaa <drive>:\windows\winsxs /y /i /s /v /h

(e.g. XCOPY P:\wfire P:\windows\winsxs /y /i /s /v /h )

run the command (it should take almost no time) and when the prompt returns, type
EXIT
and hit the Enter key to exit Command Prompt - reboot to Normal Mode Windows.

Now run SFC /SCANNOW in an Elevated Command Prompt
then reboot and upload the new CBS.log file to your reply

It doesn't seem to have stopped the error message
..here's the latest occurrence of the error..

Code:

Line 396778: 2015-07-19 08:06:56, Error                 CSI    00000288 (F) STATUS_SXS_ASSEMBLY_MISSING #952607# from CCSDirectTransaction::OperateEnding at index 0 of 1 operations, disposition 2[gle=0xd015000c]
	Line 396779: 2015-07-19 08:06:56, Error                 CSI    00000289 (F) HRESULT_FROM_WIN32(ERROR_SXS_ASSEMBLY_MISSING) #952492# from Windows::ServicingAPI::CCSITransaction::ICSITransaction_PinDeployment(Flags = 0, a = Microsoft-Windows-Branding-Ultimate-Deployment-LanguagePack, Version = 6.1.7600.16385, pA = PROCESSOR_ARCHITECTURE_INTEL (0), Culture = [l:10{5}]"en-US", VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral, cb = (null), s = (null), rid = [106]"Microsoft-Windows-Branding-Ultimate-Client-Package~31bf3856ad364e35~x86~en-US~6.1.7601.17514.BUC Namespace", rah = (null), manpath = (null), catpath = (null), ed = 0, disp = 0)[gle=0x80073701]

This is almost immediately followed by the SFC scan.

WE may be forced to do a repair install, if you have the proper media?

Are you getting the GWX messages that you're OK for the upgrade?

I'm not familiar with the exact methods MS is using for the 7-to-10 upgrade currently, especially from the download.

A repair install won't lose your current data or programs (at least in theory) - see the instructions here... Repair Install

If it's only the Service Pack, then it may install - but I suspect that it won't.

If it's a full Windows 7 Home Premium with Service Pack 1 embedded, then it certainly won't work (unless you're lucky - it gets very picky about Product Keys, but there may be ways around that)