I ran into a problem when printing a model that was very high. The model colden't stand straight up, so I rotated it until the software showed it could be printed.
Came home after 15h of printing only to find that it had melted the top 1mm of the part, probably becourse it couldn't go any higher. It looked like it had gone through with the rest of the print at the same hight, and the added material was pushed aside.
I am not 100% sure that this is the problem, but it was my first thought.
@Kyle - You got a point, this could be the Problem... 30 seconds later after looking at the 3D printer.... You are spot on! The small cable are pinched in between the platform and rod bearing base.
This also explains why the printer sometimes didn't stop the z rod motor when finished with a print and going to the bottom, it stopped after 10-15 seconds so always thought it was firmware error.