[Dekatron]

As a temporary solution you can remove the bobbin and put a metal film resistor, or two, with the same total value in its place to test the meter, then you can try to resolder the joint while the bobbin is out of the meter.

You should protect the moving coil and magnet from dust and metal swarf while you have it in the open, also protect it while soldering as the solder flux (rosin) might sprinkle on the movement that might damage its balance or stick in unwanted places dampening or hindering its movement.