Carefully inspect the dust cap that is "pushed in" and if it doesn't appear "creased" I have been told some decent 3M masking tape (the blue tape for painting @ Home Depot or Lowe's) pressed lightly on the area pushed in will allow it to be pulled out. Definately ask around however, as I am unfamiliar with your speaker voice coil dust caps and am uncertain if they are a polypropylene type or more along the lines of a wool or cloth type.
Make sure to ask around, or even start a thread, I am sure there are those out there that have successfully fixed this.
