in most cases with any potentiometer (or sensor) that reads in a bi-directional fashion you would always set it up to 'center' using a ohm/volt meter.
You take the full range of the resistance reading and divide it in half and that is your center. example: 5k pot would center at 2.5k (if you use voltage) it would serve in the same manner, a 5v pot signal would be set to 2.5v.
Now if this sensor is a self centering sensor then you would not have to set anything, it would automatically return to center. It's been a while since i've dealt with any bendi's so i cannot remember which type sensor is on these machines.

I'm pretty sure this sensor on these bendi's serve two purposes, it tells the steer indicator where to point so you can visually see it's position on the indicator (if the truck has a mast/fork position display) and it also signals to the drive controllers the position of the mast in a turn so it can cut back the power to the inside drive motor in a turn and in the tightest turn even reverse the inside motor for maximum turning efficiency. So make sure you have the mast pointed straight ahead and get the sensor centered as close as possible to center.