Charles? Sony KV-1722

[jstout66]

Tech Question:
Here's an odd one. ( or maybe not odd to those in the know.
On a 1975 Sony KV-1722 I've got high-voltage and sound and NO picture.
The filament is not lighting on the CRT. I'm leaning towards something in the instant-on circuit? Would be a shame to junk this one out, as the picture tube is actually good. * here's a pix when it was actually working.
Does anybody have the SAMS?