Hi David,
Yes the Firestone use that RF system. Today, I replaced all components in this compartment resistors and cap. It looks like I got correct HV (not quite sure). Brightness control is good as all the centering H and V controls. I don't understand why I get this wide horizontal band and a cannot expand it in the vertical sense.
Of course, I check the vertical stage and all the voltages are corrects on the 12sn7 and 6sl7 tubes. For now, I don't know what to do.
