I poked around a bit further and discovered that the +43V reference supply that was reading low at 34.2V actually had 14V of ripple on it. After removing and checking C12 a 450uF 85V cap, it was reading 135nF. Replaced with 470uF 100V cap, and voltage came up to 43.4V. Then did the whole volt and current meter calibration, and the 12mA range was no longer pegging to the left, but now rather indicating about 4mA without any load.
Put a 5K 10T pot in parallel to the existing 30K R38 resistor and was able to zero the 12mA range without affecting the 120mA. The pot was reading 2.7K, which I then replaced with a fixed resistor and now the 12mA scale was almost zeroed, only a hair above zero, so left it there for now. It seems that the circuit really wants about 2.4K in parallel to R53 (30K with the 2.7K from the pot) to properly balance the bias on the 12mA scale, but until I can get the proper resistor did for now leave both the 30K and the newly added 2.7K in place.
Both current ranges now seem accurate (as much as that analog meter will allow). Tested the 120mA with a 2.5K 10W at 250V and meter showed 100mA right on the money, verified with by DMM also in circuit. Then put a 10mA load and the meter on 12mA scale was showing also almost right on the money.
Lesson learned, check the main caps first, you dummy.
Also checked C20 (25uF 475V) at the rear output and it read 26uF with 2.0 ohms ESR. Good enough.
The C14 main supply cap seems to be good as well, kind of a pain to remove and test, so just read the DC and AC voltage across it with DMM while output voltage was set to 320V. The cap had 334.5VDC and 0.477VAC ripple across it. With the output of the power supply still at 320V and no load, there was about 1mV of AC ripple (on the DMM), and with a 100mA load about the same amount of ripple.
I think that it can now be called good to go.
BTW needed to slightly adjust the meter mechanical zero so had to remove it, and then while trying to get it back in place was wondering who came up with that plastic mounting clip scheme. What a pain in the rear to make both sides click back in place.
