Loss of High Voltage?

[Dan Starnes]

My Philco 1884 has developed issues with horizontal control. Adjustment with the hc knob has resulted in very brief if instantaneous horizontal hold. I have substituted tubes in the circuit with no improvement. Studying has lead me to the HV rectifier tube. I have substituted tubes and tested tubes to realize it is not a tube problem. I now have no picture but sound. I have not checked CRT nor have I checked any voltage anywhere yet. As a very eager yet less knowledgeable hobbyist, I welcome your assessment.
Dan