Odd issue with Heathkit H19 Terminal

After replacing some shorted tantalums on the logic and crt driver boards, I’ve gotten a raster on the screen. For some reason though, it only lasts for a split second on power up.

This thing has a very odd design where it uses the flyback secondary as a power supply for the rest of the driver board, and the oscillator sounds sickly at best(way into the audible frequency). Still diagnosing it.