Keith,
My TTB seems to be fine, but it took me a lot of tries to learn how to use it to best effect.
For the longest time I was looking down on the cantilever at about a 45 degree angle. I was lining up the reflected cantilever with the real one through the grid and it's reflection. The problem with this method is that the angles are too steep and small errors are hard to see.
Inner groove distortion was still bugging me so I kept at it. I finally achieved better results by looking at the actual cantilever from a much lower angle, just 10 degrees or so above the glass. I use the grid and its reflection to make sure I'm viewing from dead center. Then I look at the real cantilever to see if it's square to the grid. From my low viewing angle I can't even see the reflected cantilever and I don't need to. Low angle viewing makes it easier (for me) to see if the cantilever is square. Try it.
You need to do this through a magnifier of course. I have decent closeup vision but that's not good enough for this job.
Finally, as Twl said, you may just be very sensitive to this kind of distortion. I am and it drives me nuts. I've managed to get it to a pretty low level but it's still there on some records, mostly in dynamic female vocals. Still, I got through Brunnhilde and her sisters in Solti's 'Die Walkure' the other night perfectly clean. Also a magnificently recorded and pressed FFrr of Ashkenazy playing Chopin. Those are two of my toughest records for this problem. The toughest of all is Alfred Deller's counter-tenor. Ella Fitzgerald had nothing on him for shattering glass, or eardrums!
Hope this helped. If not, at least we shared the pain.
