Make sure the force trimmer switch is in the "on" position. Make sure your control input window is showing (R CTRL + Enter). On the ground, with engine running and hydraulic pressure in the system, move the cyclic a bit back and to the left then press whichever switch is your trimmer switch (I don't know the key off-hand, I have it mapped to a joystick button). Let go of the cyclic. Now, your stick position should be pretty close for hovering in ground effect.