Motorola 17T21 Flyback & Schematic

[bandersen]

Blue glow doesn't necessarily mean anything bad. A blow glow on the inside of the glass is common for power output tubes. Now if it's move of a purple and between tube elements then you've got a gassy tube.

Most common cause of no HV is the horizontal oscillator isn't running.

Odd that you don't hear any crackle from the speaker, It's field coil is a critical part of the power supply. But it must have continuity otherwise you wouldn't have any power going to that output tube,