"You could try running it with the tender shell off and see."
Forgot to mention I already did this before I posted the thread. No rattles so that's why I diagnosed the problem as the metal shell vibrating against the metal frame.
"Its hard to tell from your photo, but I think you might need hard foam large enough so that you have to force it in between the tender sides creating pressure to absorb the vibration."
I had cut out a large enough piece that it really had to be "jammed" between the tender sides as Jack had described earlier. No luck.
Everyone - thanks for the further suggestions and I will try some more today.
