[MrFixr55]

These and other sets of this vintage are notorious for cold solder joints for tube sockets and between the bard and the tabs that mount the board to the chassis. These tabs serve as ground connections and complete the ground plane for the board. Any poor joint between the board and one of the tabs will wreak havoc such as stopping the oscillator, which will redplate the Hor Opt tube, stopping the sync separator, etc. I think that the Hor Opt and Damper tube sockets are mounted on the PCB. Consider strengthening the foil traces for cathode and plate circuits and ground planes with bus wire.