Just an FYI. In Forums I found a proposed method for restarting this quest, just start a new char do the broom quest and put the DBS in shared bank. The theory was you could then start again. This does not work. I used this method, got another stone, examined and it discussed the mineral expert but never actually gave me a quest. Tried talking to guy in Graystone and all he does it the same "non quest" speech.
Somebody else suggested deleting the Ghoulbane quest and trying to talk to the Cleric guy again. Has anyone tried this? Since I screwed up the DBS already I don't want to screw up Ghoulbane. Sure I can't use it but might as well get the xp out of the quest.