Z axis jogging problems

Hi, im just printed the "new"core after discovering it had an update and got a super tight x/y axis, but now i got a problem with the z axis jogging then its going downwards.
Upwards it working fine.
I have set the brass nut that its not to tight.
Didnt have this problem on the first version of the primo core.

Seeking help😁

There might be a solution in this forum somewhere. But I can’t seem to type the right keywords.