It does depend how much it is worth to you. You could simply buy a replacement 2nd hand drive for 20 quid on ebay and send that, while whacking your own with a hammer.
You could also try opening the disk up and having a "look" at the platters
But this might count against you in the guarantee stakes
Have you contacted the vendor about this situation? Explain to them that you can send the disk back, but only after knackering it properly.
SD