I don't have an isolation transformer at the moment. I have one at work for fixing the CRT power supplies I do there, but I can't get it right now.
I never get any voltage on the UC3844's VCC pin, but the OUTPUT pin has some voltage on it, around 0.5v.
The primary side of the main transformer looks good. All of the pins on the secondary side have a resistance of less than 40 ohms between each other.
It has 2 schottky diodes on a shared heatsink. One of them looks normal with around 0.2v drop on each of the diodes in it while the other has around 0.01v drop on each. That is testing them in circuit.