Hello and welcome!
The bottom photo shows an "old baby". An "very old baby"?
Would be interesting to know what you paid for it. To assess what you can lose at all. In the worst case.
In germany a new THR10C costs +/- 260 - 280 €!
"Rattle" ? ... can you describe that in more detail? More details on "Rattle" are helpful.
What is rattling where and how loud? A loose screw, a loose cable, ... it always rattles? ...
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"The seller insists it works fine and didn't rattle when it was shipped ?!?!?"
Now find out the truth - there!
Best way: RETURN TO SENDER!
If possible: Immediate return!
All this reminds me: "seller sells a defective ebay item!" ...a neverending story!
eBay Buyer Protection is just made for that! MONEY BACK! without a problem!
Good luck! Others - from this forum - will surely answer you as well.