What if you try measurements on that range, what you get?
I'd suggest investigate A10 PCBA and measure signals, if there is any issue with signal path used for 70mV range.
Does it pass calibration zero?
You may want to start by looking at the A10A95 (Also listed as A10A3) card.
It is a daughterboard soldered on the top middle of the A10 card.
Remove the cover of the circuit board and the foam and visually inspect for burned components.
Might also check A10K2 as when the relays get old they can cause noise issues that will cause errors.
FLUKE5790A Error 408 A10 Transfer 70mV Range
What if you try measurements on that range, what you get?
I'd suggest investigate A10 PCBA and measure signals, if there is any issue with signal path used for 70mV range.
Does it pass calibration zero?
You may want to start by looking at the A10A95 (Also listed as A10A3) card.
It is a daughterboard soldered on the top middle of the A10 card.
Remove the cover of the circuit board and the foam and visually inspect for burned components.
Might also check A10K2 as when the relays get old they can cause noise issues that will cause errors.