Need Help Making Windows Repair Disc USB

I have a multiboot USB made with YUMI for some general repair and virus removal, but one thing it lacks is Windows Repair Discs for startup repair and repairing corrupt files with sfc (If Hiren's Boot CD can be used for this, let me know)

I do have a repair disc for Windows 7 x64 on a CD, but that loads much slower than a USB, and not having to worry about physical discs and only a single USB would be nice.

Today I decided to give it another shot. I used Format Factory to turn that repair disc into an ISO. I then added it to my YUMI multiboot as an unlisted ISO. It was able to boot, much faster than the CD, but unlike the physical CD, it was unable to detect my Windows installation. I'm guessing this has something to do with the disk looking for the installation on the USB, instead of my hard drive.

While startup repair was then pointless, as I remember in the past using Startup Repair would overwrite the USB boot sector with the Windows 7 boot sector, I was able to use the command prompt. I then input the sfc command:

sfc /scannow /offbootdir=c:\ /offwindir=c:\

It said it was beginning repairs and would take some time, but after a couple minutes, it had not started scanning at all, just saying it was starting.

So, can anyone help me?

 

It turns out the sfc scan DOES work, as after I left it alone today for a few minutes, it did finish and found no problems (which was expected since my Windows runs fine), it just didn't show a progress %.

However, there's still the issue of my USB not recognizing the Windows installation on the hard drive, while the repair CD detects it fine. I believe this is because it is looking for a Windows installation on the USB the repair disc is on, instead of the hard drive. How would I edit my repair USB to have it look on the hard drive for the Windows installation instead of the USB?