HELP!!! Hyfire II Sounds like it going to blow up!

Put some thin foam tape or similar (weather stripping - sticky one side) on the bottom of the lid.
You can probably get a small roll at your local hardware store.

Dave, my aching head thanks you!

or a piece of electrical, duct or equal tape along the top edge of the hopper to insulate it from the lid. Anything would probably work to eliminate the metal to metal contact.

Good luck!! Stay warm!

It's actually not the hopper but the top lid of the stove itself that was making the racket. Hubby was thinking of putting some sort fire proof insulation to stop the rattling, but first we wanted to see how it did once the piping was installed from the top into our ductwork. He did that yesterday and so far, no more rattling. The pipe must be holding the lid down in place. Fingers crossed!