You should have more than 0.7V across BC of Q484 in normal operation, E is connected to the -12.6V output, B should be approx -12V and C +2V.
Another common problem is some of the larger film resistors, they either drift up in value or go open circuit, this is a problem in the 140, 141, 180, 181 etc series. R485 & R489 are probably most likely to suffer from this in the circuit part you posted, as they have 90+ volts to drop. Had this with that 180A in the horizontal section, both 22.1k resistors had been cooked and gone up in value.
David
factory