The big white one is dead, just measured. I even saw it light up as well.
As far as my brief search reveals these 'paired' resistors are no longer available - so you might have to buy 2 and possibly drill a hole in the PCB to accept the other resistor wire.
I don't know about transistors, not even sure the meter is capable.
Well, we could try and teach you - but this would be a steep learning curve.
Would it be totally silly to try and replace the for-sure-dead resistors (r67, r69), and then try again, with the actually working meter? Would this be too risky, if other parts died?
Yes, without verifying the state of the outputs and the driver transistors - not a good idea. And even when you have done this I feel sure you will need a DBT to assist with further diagnosis/troubleshooting.
Would it be anything close to a conclusive test, if I change the two, and I am then able to adjust the bias, and so on, without anything else dying?
Knowing what we know now, that the emitter resistor(s) died, I think it very likely the output transistors (qty 2) are toast.