You can disable the headrest auto-adjust with TechSTream (see bottom of Page 01-24) on the attached PDF.

 

Thanks for you help. The reason was the connetction to the motor of the leveling adjustment. The part of plastic which is connected to the plug with wiring was broken apart from the motor housing. So it was disconnected. I fixed it.

 

Glad to hear it was a fairly easy fix! Now, enjoy that LS!