Well I started on my cross slide today(if measuring can be called starting). As you can see it failed the rotation test, its a bit of a banana. That's a 0.002" feeler gauge, its pretty even both sides and on the corners. In fairness to the people that made it I did bottom the crossfeed out hard enough to bend the screw so maybe its not all their fault.
I'm thinking I should scrap the bottom first in this case, as I think it will be easier to scrap straight down as the corners are pretty parallel.
Stuart