what center pulse rudder you have set in SERVOS - TYPE ?
for servo rudder 3515t is exact pulse center 760us

Hello Franz, the center is set to 760, see attached screenshot.
In my EdgeTX remote, the output at 1500, but i think this is not relevant as I use FrSky Fport....

I also attached my complete Spirit-4ds-file.

Regards, Chris

I only have one idea left
for that size of helicopter those rpm are few
try 2700 rpm
for me you have few rpm rotor
my 580 use 1900-2000 rpm and the helicopter the smaller it is and the more RPM you have to use.
start at 2300 rpm and increases the rpm until you see that it flies well
for me a helicopter size same as yours It must fly at almost 3000 rpm
I don't know omp but I can tell the turns of my helicopters
my sab goblin raw 580 1900/2000 rpm
my trex 600l dominator 2300rpm
trex 450 3000rpm
trex 600cf 2100rpm

I think everything is ok you didn't find the RPM exact for your helicopter
Maybe the problem it happens only in a certain rpm range can disappear exceeding those rpm
my old helicopter trex 450 it's the size closer to yours and I used 3000rpm
PS
the manual omp m4 has RPM min 1400 and RPM max 3000
Find the right RPM for you

No, the rpm are correct an quite perfect for this heli. Attention: this ist the M4max, not M4. The recommended rpm were posted on page 2, and I am not Tareq
And as I stated before: the problem grows with higher rpm.
I will commence tuning the governor, maybe the path to success lies there

Let me know how to solve the problem.
The tail he was going crazy for an esc that wasn't working well.
I'm curious to know
Ps
Thrust bearings they are mounted exactly?
the part of the spheres towards the outside.
The part with the edge towards the t hub

I understand the problem.
Online i found many posts of problems of the tail of your helicopter model.
The problem is the servo tail, you just have to try another servo tail (a different brand) and you'll see that it will go well.

Hello @franz88,
finally the weather has been good enough....
The wagging is nearly gone, a bit is to be seen, but only when hovering stationary. But it's a lot better now.
What have I done:
First I made the tail-mechanics even more smooth, I widened the ball links a bit more so there is nearly no friction but also no loose connection.
After testflying it was better, but still wagging there.
Then I reduced the p-value of the esc from 4 to 3.
Test showed a little bit but not much better.
So I also reduced the i-value in the esc also from 4 to 3.
Now it was better, as decribed earlier. I stayed at the esc setting with p=3 and i=3.
For me as a scale flyer it is okay, don't know if a 3D guy would complain about rpm holding performance.
I did some heavy pitch pumps @2000rpm, the rpm fluctuated +-150 then. When I am flying smooth the rpm fluctuates +-80. Is that value okay?

Regards, Chris

did you see?
the first thing that I told you is the tail must be smooth and without mechanical impediments.
That's a small model a little effort it doesn't make the tail work well.
On helyfreak it's really full of posts on your model with tail problems.
If you can't to make fluid at 100% the tail the problem I would make it disappear inserting a tail servo with more kg of thrust.
Put a tail servo with more force but don't forget what speed is needed for tail servo.
many helicopter models They have manufacturing defects.
But I assure you that the spirit has a tail hold the best in the world, but if there is a mechanical problem it's normal that it's not good.
your tail linkage must move almost as smooth as oil both right and left.
and remember to try to move it with your fingers when the helicopter is turning and no when the helicopter is stationary.
PS
from what I understand that that tail servant it's not good now decide if you want to be satisfied or do you want the top from your model.
I had problems too with the servants included in the helicopter kit, on my trex 600l dominator was mounting align bl815h with manufacturing defect and it took me a long time to convince me that I had to change them.
In fact now before buying something I read online the experiences of other people and if many people they have problems I change the article why if 6 people of 10 they have problems you may end up in the 6 who have problems.
read online and you will see that many people with your model they have tail problems

I had nightmares with the tail and I also listened to Franz88's advice and he was right about the tail control having to be smooth. However, there was still a bit of oscillation that was eliminated by inserting a shim between the gear wheel (for the tail belt) and the motor. In fact, when held up to the light, you could see the belt was not centered with the wheel.

La pagina del manuale in italiano è 22. In allegato l'img della shim

I had tail wagging in 2 helicopters (not M4 max) and in both cases the problem was solved after replacing the tail servo with a better servo. To test whether the ESC is the cause of tail wagging, you can set P and I to 0 for a short test flight. I use Spirit GTR and YGE. Especially in M4 (not max) the tail servo is slow.
Of course I agree with franz88 that the tail mechanics has to be smooth first before you try other things.