First, make sure your elevator chains are good and tight. It's probably time to replace them, though. After a while they stretch enough that they're hard to tighten properly. While you're at it, inspect the sprockets for excessive wear. It's a bit cumbersome replacing the chains, but it's not too hard of a job. I don't know about metal or poly paddles; we've always had rubber.
You should check your incline auger, as well. If it's worn out it can't move grain fast enough and plugs the clean grain elevator.