Just now, I had a major happiness by deciding I had nothing to lose and trying a trick. I just got a 12 inch Bausch and Lomb lens today from fleabay. When I opened the box and looked at it, my heart sank--my 136 dollars was wasted for sure. The inside surface of the rear lens doublet looked like somebody polished it with steel wool. Scratches so bad it was totally worthless. So I got out a pice of cotton and put a dab of Ultra-Brite Advanced Whitening toothpaste on it and rubbed it around a couple minutes. Then squirted some windex on a piece of toilet paper to clean off the toothpaste, and the lens was clear as a bell. Amazing. Now I can proceed to try to repair the 1912 Betax #4 shutter which doesn't work, which is why I got the thing for 136 bucks. Wish me luck.