Sure enough that was the problem. Thanks man
Funny thing is the diode in the optoisolator tested good at room temperature, but once I hit it with cold spray it would stop working. And even stranger testing with a multimeter it checked out OK, no matter what the temperature.
I replaced it with a another IC from an old power supply, same chip but lower gain in the transistor and it gave me some really mad screen problems. Found another similar IC with similar specs and works OK now. Touch wood