Follow up on the Ebay Low-Bid wins; The $21 Canon 135mm F3.5, late version in black, described as severe coating separation, was actually a cemented pair that had come undone. Elements 2/3 to be exact. Took about an hour and ten set-screws to get to them. I used 99%isopropyl alchohol to take the Canadian Balsam off as the lenses were already split. They are clear now, and as an experiment I am going to use some index-matching gel to see how it affects reflections. The lens looks clear, and given the retaining ring that pushed the elements together, I will bet it works. Otherwise, I will re-glue them. You have to heat the elements to 300F for the glue to work, I am not ready for that yet, and would practice with junk lenses first. For $21 I figured the focus mount alone was worth the price.
BUT: Extreme haze, severe coating separation is probably the cemented elements going. The coatings were perfect.