[old_tv_nut]

These caps are encapsulated and only have 12 volts on them according to the SAMS and are therefore very unlikely to suffer from silver mica disease.

If you have not done the AFC alignment procedure yet, it is really important to do that before trying to trouble-shoot further. The first part of the procedure makes sure the phase detector is getting maximum amplitude signals, and the second part then makes sure the oscillator is at nominal frequency when the detector output is zero. If this second condition is not met, the oscillator will try to run off frequency and the detector will try to develop enough control voltage to center it again - but if it eventually drifts too far off, control will be lost. In this case, the color killer circuit may decide there is no burst and shut off the color unless it is cranked to one end to force color on.