Chris,
Tonight I fired up my RCA TC-166(KCS 40A) chassis with the 5AXP4 test crt and put a DVD test pattern on it. To my surprise it shows the same concave edges you're experiencing. I don't remember it being like this, but I probably never used a test pattern when working with it earlier. This weekend I'll attempt to slide this back in it's cabinet and see if the 16GP4 makes any improvement. Right now I'm not sure what to make of it.
