Found a Philco

[Chad Hauris]

You could supply a signal from another tuner into the IF stages to rule out any problems in the tuner, provided the Philco uses the modern IF frequency...also have you checked all screen voltages on the IF tubes, maybe a shorted cap burned out a resistor, also could be a bad video detector diode? What is the negative AGC voltage...you may need to bias the if stages with adjustable negative voltage from a power supply to check how they respond.