a look and found these:-
http://www.ehow.com/how_2265610_remo...owel-pins.html
Suppose this one would help by not damaging the hole if you try and twist the dowel out with a stilson or mole grips. But seems too easy the way he says!!
http://www.youtube.com/watch?v=OmMnuA4HUn4&hd=1
Once again not my recommendations but might give you an idea or two.
Maybe a bit of heat on the area!! Flood it with plus gas or such.
Good luck with it.