iPod Video syncs to iTunes, navigates great, but won't play music

My situation is very similar to this user here, iPod Doesn't Play Music or Video

My iPod video will sync to itunes, I can navigate through the menus, but when it comes time to play the song I've selected, it will not play.

The song progress bar will not move, BUT the play icon will appear in the status bar.

I have swapped a working hard drive into this iPod, from another working iPod.

However I did not change the headphone jack.

Could the headphone jack be the issue? Not telling the logic board that headphones are plugged in, hence why the music wont start?

Or the hard drive controller chip could be bad as well.

Not sure, any ideas as to whether or not a new headphone jack would do the trick?

Cheers!