ModelCraft GT3 2.4GHz Notice D'emploi page 46

Use the driving trim button (see fig. 1, item 6) to set the centre position for the
throttle servo (CH 2).
The button is operated according to the steering trim button. The value can
be adjusted between forwards = "Forward (F 30)" and reverse = "Backward
(B 30)".
If the display is exactly at "N 0", the exact centre position is reached. The set
value is stored automatically. Use the Enter or ESC button (see figure 2, item
11 or 12) to switch back to the operating display.
Set the centre value precisely even if you are using an electronic
speed controller rather than a throttle servo.
46
NO.
5.8
V
TRM
CH
F 2
TRM
CH
B 5
TRM
CH
N 0
Figure 7