[morzh]

400 micro-Amps, not micro-Volts.

Full deflection current will move the needle to the far right when put through the spindle coil, to which tthe needle is attached.
Then it is simple Ohms law: your full resistance (including the one of the meter itself, though it is rather small) will go into I=V/R formula, where the V is your voltage.
You could simply measure the resistance between the two contacts of your resistor (with the resistor itself disconnected) to see if it is 250 Ohms, or it is more than that. If it is more than that, you need to trace all the resistors that are in series with that resistor in question, and then your resistor will be

R-needed = (10V/0.0004A) - R-measured, or rather R-needed = 25kOhm - R measured.

If your R-measured is more than 250 Ohm, you need to find out what it is and why it is a part of your circuit, which (your colored part) shows straight wires.