I was talking about the ADC units, as it is likely that each ADC channel in the chips has a power rail set, and it is possible that the diode dying drew enough current to pop an internal board via or blow open a trace that powers part of the chip, crippling the one part. I saw the hybrids are fine. Thus taking the 2V5 rail, soldering a flylead onto the capacitor and doing a simple resistance check on the pins WRT this supply and on another working channel will likely show up a broken trace. Probably you will find each channel supply has a decoupling resistor on it. Simple enough to do, and not dangerous or tedious. This was brought by the chip diode having the negative supply on both sides, while the others have a positive supply on the one end. Losing a power rail probably did not affect the hot running digital logic of the chip, it could have been a supply to an ADC front end amplifier that went out, and this barely drew any power in the first place so made little difference thermal wise.
If this unit is fixed a set of glue on heatsinks on the bigger chips to cool them down would not go amiss though.