@Phaedrux

I did Some tests now, and on the first one was still some decent Z banding - but in a random order!
Then I placed a model right in the middle of the bed (if it would be because of thermal expansion, then it should be most visible there, I think) and run a test without and with Bed heating (Bang-Bang).

This is the Result:

Hell YEAH! This was it!
@Phaedrux can I offer you a Coffee?

Fun fact: I measured the cycle time for the Bed heater turning on: It takes between 15-17 Seconds

So the next question is: Does PID solve the problem entirely?
And how common is this problem? I searched a lot for types of z wobble, but this one is new to me, although it makes a lot of sense.

Edit: Is there a way to change the name of the topic (or mark it as solved)?

I used M307 with the Fnnn parameter to set the frequency without luck. But Qnn on M950 works! Thanks @Phaedrux !
Running now inaudible at 20 Hz.
Does anybody know if this could be unhealthy for the PSU Capacitors?

@Dad003 I think the remaining artifacts could be to some amount z-wobble. However, the biggest point was definitely the Bang-Bang Mode.

Now here is something interesting: I changed to PID-Mode and the wobble is very present like in Bang-Bang mode! I'm running a new auto tune run now. I hope, that helps.

@theruttmeister yes. I did most of my testprints in the corner. However with Bang-Bang ON it is still noticeable. I am trying it now it PID PWM mode.

@Phaedrux

I did Some tests now, and on the first one was still some decent Z banding - but in a random order!
Then I placed a model right in the middle of the bed (if it would be because of thermal expansion, then it should be most visible there, I think) and run a test without and with Bed heating (Bang-Bang).

This is the Result:

Hell YEAH! This was it!
@Phaedrux can I offer you a Coffee?

Fun fact: I measured the cycle time for the Bed heater turning on: It takes between 15-17 Seconds

So the next question is: Does PID solve the problem entirely?
And how common is this problem? I searched a lot for types of z wobble, but this one is new to me, although it makes a lot of sense.

Edit: Is there a way to change the name of the topic (or mark it as solved)?

I also think that the MOSFETs are broken. If your solder skills are not to bad and you have an N-Channel MOSFET with specs like 40V 20A lying around, then even a non SMD type will fit onto the pads (without the large surface of the MOS). You dont even need an additional heatsink if your R_ds_on is not to large. I would recommend less than 50mΩ.

I had an issue with a short circuit in a heater (or between two), causing similar problems. I fixed a board like described - and works again perfect!
Downloading the Schematics (if you have KiCAD) will help if you are unsure about which Mosfet belongs to which output. But here it seems obvious.
Good luck!

@Phaedrux good idea!

@Phaedrux Yes. I tried PID as well as Bang-Bang but no luck. However I switched back to Bang bang since the PWM signal from the PID control caused more audible noise.

Edit: I am not sure I covered this explicitly in my tests. I will rerun this right now, to be 100% sure.

Sounds to me like the two wires in the middle of the motor connector need to be swapped. Try that!

What are your motor currents, what PSU do you use, and which printer is connected to it?
It sounds to me, that your PSU is at its power limit and therefore shutting down sometimes, causing skips. However since only X seem to be affected, I think it could be a mechanical issue or driver shutdown due overheating. Would you mind to share your config file?

@BDubs Unfortunately, as mentioned, I even swapped my Hemera hotend on it, which was working fine on the other printer. I am very sure, that the Nozzle,Block or heat brake is fine...