You're sure your doing it right? there are two CAL trimpots and the meter's internal resistors must not be in-circuit when doing that.
First is applying 50uA and setting the parallel trimpot R1 so it's at full-scale. I'm assuming this step is where the party stops. Did you try (it) full-scale current with the trimpot disconnected? Your trimpot might be the wrong value is it 100k or 200k etc. Lift a leg on it, to see what the raw meter movement can do. Army CAL manuals (bottom of webpage I linked) is applying to 50uA/250mV input jack.
(Second step is setting the meter circuit to 5,000 ohms with the second trimpot R2).
A few different
Series 6 models. Not sure which you have.
Can you see the main spring calibration, they usually solder the one end into a U or fork.
Otherwise, I don't know how to re-magnetize it. I would blame the magnet last.