Joined: Jan 2013
Posts: 1,339
Likes: 7
From: Westfield, MA
Bikes: 1983 Univega Gran Turismo, 1970 Schwinn Super Sport, 2001 Univega Modo Vincere, Self-Built Nashbar Touring, 1974 Peugeot U08, 1974 Atala Grand Prix, 1986 Ross Mt. Hood, 80's Maruishi MT-18
Spray some penetrating oil down into the steerer tube and let it sit a day or so. Try putting the bolt back in, but leave it loose. Give the top of the loose bolt a whack with a hammer (put some wood between hammer and bolt). Hopefully this will disengage the wedge, it's probably rusted in there.
EDIT: don't leave too much of the bolt exposed. Leave it like 1/2" above the top of the stem. That way you can only drive the wedge 1/2" down into the steerer. You don't want to drive the wedge too far down.