Running nose wheel takeoff, as described in the manual

Hi,

I have tried to follow the manual on how to perform a Running nose wheel takeoff, page 272. There are some things I cant seem to get right though.

Particularly this section:

Disable the autopilot by pressing the AUTOPILOT OFF button on the cyclic control stick. Reduce collective pitch to minimum by lowering the collective control handle to the lower stop (full down). Apply the wheel brakes. Push the cyclic control stick to the forward limit and proceed to turn ON the autopilot ROLL-PITCH channel by pressing the corresponding button-lamp on the autopilot control panel and checking for green light illumination. Pull the cyclic control stick to the aft limit and release the stick force by pressing the TRIM button on cyclic control stick. The forward and aft deflection limits of the cyclic are determined by the absence of thumping noise as the main rotor blades strike against the flapping hinges of the rotor assembly.

What is the activation of the roll-pitch channel supposed to do? I can't distinguish any difference with it on or off at any stage during this procedure.

Pulling the cyclic to the aft limit and pressing the trim is supposed to do what? same as for the AP channel, can't distinguish anything. Is the trim supposed to be held down or clicked? should the cyclic be returned to center afterwards? doesn't seems so, why release the stick force in the aft position then? If I let it stay in the aft position the helicopter start to move backwards when releasing the brakes and increasing collective (quite expected if you ask me). Is this dependent on trimmer mode in the options? I have the "no spring and FFB" one, should I have "default" for this procedure to work?

Then we have this:

Release the wheel brakes. Smoothly increase collective until the main landing gear begins to lift off the ground. Maintain the nose gear on the ground. Smoothly (3 - 5 sec) push the cyclic forward 1/2 to 2/3 stick travel to begin the ground run and establish a nose-down pitch attitude of -8 to -9° below standing pitch (2). Control the pitch angle during the ground run by maintaining the blade tips of the rotor disc on the horizon line. Smoothly increase engine power to Takeoff setting in the ground run.

"1/2 to 2/3 stick travel", relative center or aft position as per above?

This never happen to me:

At approximately 40 kph the helicopter exhibits a tendency to pitch up and sink onto the main gear, followed by a reversal and an energetic pitch down.

In what way do I misinterpret the instructions?

I know there are other methods described here on the forum and in videos, more based on trial and error, but I would like to know if this official method do work if performed correctly and if someone has successfully done so?

Thanks!