I have an enlarging anastigmat which I am told has some separation of two elements. It looks like a partial halo around the center of the lens. I was advised to place the cell in a cold oven, very, very slowly (over several hours) raise the temp to ca 175 deg F., for a couple of hours, then, equally slowly, lower the temp and that PERHAPS the problem might resolve. As it is now, I have a decent paper weight. Any comments or suggestions are welcome.