Create a back-up of only systems files?

I'd like to create on last back up before I go Windows 10, so I can get back to where my system was just prior to this if I want to. I have a factory reset reset button on this machine so I will always have the option to downgrade to Win 7 again if I want to. With a recent back up this makes it easier to recover my system to where it was just before upgrading to 10.

I have all my files backed up on ext drives, however is there a way to make a disk image of only systems files, omitting all my data or do I need to remove all my own files and then put them back?

Everything's on C yes. Well, not everything, but all my recent work. Cat pictures and all that. If there's no easy way to do this I'll just double back everything up, wipe my drive and then reload everything back on to my laptop afterwards.

I already have two images. Well I thought I had, seem ones of the folders now appears to contain nothing so not sure what happened there. In any case, I always have the option to factory reset this machine, so I can always get back to Windows 7.

Finding an empty folder in an image where there should be files would be a concern for me.
What program did you use to create the backup images ?
Many of the backup programs have logs you can view, there may be info in there about an error.

I'm assuming you are browsing the backup image file, and that's where you see files are missing.

Just using the built in Windows software, following the steps in the tutorial.

I don't use the Windows built-in imaging utility so i don't know what logs, info, etc. are available.
If no-one reply's here with help, you can ask a question in the tutorial.

It's not really an issue, unless the next back I create goes through a wormhole again.

OK.
You could try Macrium Reflect free and see if it copies the files correctly, if you want to compare it to W7 Imaging.