i don't know if such things can be helped with via forum, but i try

I have 2 Leadshine L7P-400 / EL7-RS400P drivers with 2 ELM2H-0200LA60F Servo-Motors mounted on my lathe:
viewtopic.php?t=11657
400W, 23bit opical encoder, 230V, pretty high-quality
My problem is:
No matter what parameters i use, default, softer than default, one-click-tuning, simple-tuning, or after a first manual tuning... my Z-axis is cheeping like crazy! It really hurts in the ears, and is bothering extremely.
Is here anyone, who is really good in such things and who can tell me, what else i could try to quieten this axis?
It seems like the sound comes from the motor and ball screw, maybe the direct-driven and relatively long ball-screw makes it even worse.
The cheep is exactly at 8kHz, and only comes up when standing still. As soon as i try to spin the ballscrew in any direction, the cheeping stops.
If i move the axis a few mm via WMPG or keyboard, the cheeping gets louder or quieter sometimes, but not every time.
Does anyone know what i can do to at least quieten this a bit?
Here is a short video with audio Thank you,
Marc