Diagnosis
That rattling is almost always the basket handle. On these models, the black plastic handle can work itself loose from its mounting points on the wire basket frame over time.
How to Fix It
Unplug the unit and let it cool completely. Turn the basket upside down. Look where the ends of the plastic handle clip into the metal frame. You'll likely see small gaps. 1) Firmly press the handle ends back into the frame clips until they snap into place. 2) If it's still loose, you can use a small piece of aluminum foil to shim the connection. Just fold a tiny bit of foil and wedge it into the gap between the plastic handle end and the metal clip to tighten the fit.
If That Didn't Work
The noise could be coming from the fan if something like a small piece of breading or a seed got past the basket. Unplug it, let it cool, and use a flashlight to look up into the heating element area. Use a dry brush or a can of compressed air to gently dislodge any debris.
Heads Up
Don't ignore this. A severely loose handle can eventually detach when the basket is hot and full of food, which is a spill and burn hazard.