Extreme screen "rot" on an ADM-3a (an ebay auction)

middle. It's referred to as "cataracts". I don't know if it's mold, but it basically results in the breakdown of the PVA bonding compound that holds the safety glass to the face of the tube. To remove it, at least on the TV tubes, you take the the tube out of the set, put it neck down in a large bucket/barrel so that it's supported, and use a heat gun to heat up the screen. After a while, the PVA will soften, and the faceplate can be gently separated from the tube. Don't pry it up - try to gently induce air bubbles under it with wooden shims and heat. Once the bond breaks over most of the tube, the glass should come off without breaking. Then you clean out all the PVA gunk, and reattach the safety glass with packing tape along the edges.