I had a terrible one, the head sheared off and I got it to move a bit with an air-chisel but not much. Next I drilled it out and drifted it a bit and also was able to put a greased washer on the exposed threads followed by two nuts that I could tighten to pull what was left out. I think I used two nuts as one felt like it would strip. The new one was lathered in anticorrosion wax.
Let us know about the tool !
http://www.ebay.co.uk/itm/AMBERSIL-6...-/272148220214