Steve, You can get real agressive cleaning the back of a lens. I've even used 600 wet-or-dry with Windex as a lubricant to clean off stubborn stains. Just a little pressure and they will come surprisingly cleaner. Later . . . Jim
Steve, I really can't tell what is on them, but I have had lenses that were on with plaster. I have taken a guitar or piano wire while keeping them wet; and cut them out. You have to be patient by putting all the pressure on cutting the plaster. Hope this helps you now or in the future. One looks broken, but this may help you if both of them aren't already broken.