I purchased a used Sigma EX 180mm f/2.8 APO HSM EX DG OS for Nikon from ebay.

The lens arrived with the lens cap cracked as some force had been applied to the front of the lens when shipping. The glass elements appear undamaged, however upon attaching to the camera, I noticed the focus system is completely broken.

The lens will not autofocus and the manual focus ring turns, but does not actually focus the lens.

Fortunately, I was able to work things out with the seller in Japan, he initiated a postal claim for shipping damages and my money was refunded.

I now have this $1,000 paperweight in my possession, and I'm wondering what possible avenues I could explore for having it repaired.

This is a Japanese lens in the USA, so it is gray market, and I believe Sigma charges an additional $250 dollars on top of the standard repair fees. This may put the cost above what its worth.

I have never dealt with a broken lens that will not focus at all, and I am curious as to how difficult a repair like this would be.