iPod Classic not syncing all my songs from iTunes

Background: I've had my 160GB iPod classic for 5+ years and been using iTunes for close to ten years. I'm using Windows 7 on my PC and up until recently I've been updating both iTunes and iPod whenever updates are available. After the horrible experience of upgrading to iTunes 11 and trying for over a month to get used to working with all the annoying bugs and compromises in functionality that Apple stupidly introduced into what was once a really good piece of software, I decided a week ago to downgrade to version 10.7. I went thru all the necessary steps to make this downgrade work, eliminating the various error messages, etc, and it appears now that my earlier version of iTunes is fully functional.

But when I connected my iPod to sync new songs, I kept getting a message to scan and fix the disc on my iPod. I wasn't sure if I should do that so I ignored the prompt a few times. Then last night I decided to restore my iPod and start from scratch. The disc error message has gone away, but now it is not syncing all the songs it is supposed to.

Af far as I know there are no broken links and all the songs in my music library are located within iTunes, so that is not the issue. There may be some songs with the same title and artist but that appear on different albums, so those should not cause a problem. At this point I have too many songs to fit on my iPod so I have selected to sync only checked songs, and I have unchecked over 1000 songs in iTunes, so that when I connect the iPod, it doesn't tell me that there is not enough free space to sync the iPod, it just syncs the checked songs.

Before restoring my iPod, I had 14161 songs in iTunes, with 1105 of those songs unchecked so as not to sync them in the iPod. I did the math and that left 13056 songs that are checked, and that was how many songs showed up in the iPod after syncing it, with about 1GB of free space left on the iPod.

Now, after restoring my iPod, I get only 13009 songs showing up in the iPod, meaning 47 songs are missing (with exactly 1.4GB free space).

How can I troubleshoot this to find out what songs are missing and why, and then fix it? Is there an easy way to approach this daunting task? I am really fussy about my music library and am not the kind of casual user who just loads a bunch of stuff on my iPod and doesn't care if there are duplicates, broken links, missing songs. I manage my own library very assiduously each time I import new music and make sure it is tagged and filed correctly according to my own system. I want to fix this issue.

Could it be a problem with me using a newer version of the iPod updates with an older version of iTunes? And is there a way I can correct that, possibly downgrade the iPod software version I have now? Would it be worth the trouble to try restoring the iPod again, and if so, what precautions do I take to prevent the same thing happening again, where not all my songs get synced to the iPod.

Thanks to anyone who can offer some helpful advice...