This is what the cable that is to be discarded in the Truck looks like. The Bad Bearing Picture...
So it comes down to Mechanical or Electrical.... Mechanical be sure the Truck can move up and down easily... Could be a Z Motor not mounted correctly. Or Electrical.... Did you plug the servo motor plug in 180 degrees out?
Is the FFC Cable seated correctly...
I have concerns... Can you look over your FFC or the big flat Cable that brings power to the Z and brings back encoder data.
Make sure you don't have a mix of 18 and 14 pin parts...
AL
In the Old Z Picture, it is a 18 pin not a 16 pin...