I seem to remember it is a regular blue LED totally separate from the PCBs. I do not think it will be difficult to troubleshoot. In any case, the main thing is the reading. I can always hang a flashlight by the panel meter.
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I measured the voltage across the 1K resistor and LED and they seem correct: Total 9.75V, Resistor 7,00V, LED 2.75V. (The 1K resistor in my PCB is marked as "R12"). That is 7mA going through.
I connected a second power supply to add some current and even with something like 35 mA it is still nowhere near the brightness of the other unit. I guess the LED might be marginal.
I think I might just leave it as it is and use it somewhere where backlight illumination is not that important.