Maybe the raised styrene pieces on the second ring from the center or are they donor parts? Looks like they're casting a shadow.
I don't know if you have this image or even if it would be of much help.
http://i658.photobucket.com/albums/uu302/scratchyimages/Death Star/ds200_zps370bbe8f.jpg
looks splendid Rob!!!
But I am a little worried about the slightly comvoluted surface of some of the pieces. I've determined they're not air bubbles, but little specks of crap that somehow stuck to the backside of the vinyl. Transferred from the exacto blade, picked up from the cutting glass, maybe on the model itself.
Not sure paint wil hide these or not. May have to re-do a couple pieces, but that would be simple enough I suppose.