Remove dash

On a similar note, I have a 64 Dart 4 door 273, and I was 'Armor-all'-ing my dash, and the little knob/button in the center of my speedometer popped off, leaving half of it inside, behind the clear plastic. I would like to get that out of there and maybe re-glue it.
Does any one know how to just remove the clear plastic?
(...and you should see how bright the flourescent paint on the speedometer needle is where the sun never hit it!!)
http://d.yimg.com/kq/groups/1437016/tn/117671849/name/002.jpg[/IMG
That's before the knob popped. (Cheap toy camera photo)