I am pretty sure I know what is going wrong. The Sams instructions for aligning the color AFC are easily misunderstood. It talks about adjusting the oscillator transformer for max VTVM deflection, and then adjusting the burst transformer for maximum deflection. I was interpreting that to mean maximum negative DC bias at the test point.
But I found an RCA book that explains that oscillator transformer is peaked for max negative voltage and the burst transformer is peaked for maximum voltage. The Magnavox Tabs Manual explains the theory of the phase detection circuit too, that is, the burst is supposed to be 180 degrees out of phase with the oscillator, and they are supposed to be approximately matched in amplitude. So peaking the oscillator transformer should make the test point voltage as low as possible, and peaking the burst transformer should the raise the test point voltage as high as possible.
The naive reading of the Sams instructions results in the opposite, which minimizes the ability of a phase shift in burst to phase shift the oscillator. This would also explain why a weak burst amplifier tube would cause limited range for the tint control. It also suggests that peaking both transformers isn’t ideal. It is just a starting point, and it is best to touch up both transformers so that oscillator wave and burst wave are the maximum amplitude for which they can be adjusted to also be equal amplitude.
