Bill, how did you clean it? When I know this I might be able to help.
If it was coal dust in the fibre then vacing it may well have made it worse. You could have beaten it farther into the pile as opposed to removing it from the same.
If you have used heat at all then it might not all come out as you may have "bonded" it to the yarn. Other than that as it is pure wool then just flood it and you should be able to restore it.
Best, Dave.