That's the weird thing. None of my gears were worn down or broken in any way that I could see. I even spun the worm gear by hand and it rotated the big gear to spin the odometer just as it should. Is it possible that there's a little motor encased spinning that worm gear and it could have stopped working?
Either way it doesn't matter, because when I popped my odo back into my speedo and plugged the cluster back in, the speedometer refused to work. I said screw it and just bought a used cluster off eBay for $30.