the motor controller should be mounted in the same place/area that MIB controller is.
it would be a larger square box with a blinking light on it, there might be more than one, it would also have some harness connections and larger power cables connected to it. Usually there is one for drive, hydraulic and in some cases power steering. I believe in this truck there are probably only drive and hydraulic. In most cases the drive controller would be mounted on the RH side and hydraulic controller on the LH side of the drive controller.
If you do not see anything like that there then remove the panel behind the operator and it may be mounted there. Most reach trucks have the motor controllers mounted in the same area, some do have components mounted behind a panel behind the operator.
If you don't have a handset or laptop program to access this controller then yes, you will need to call a tech that does have these tools.