Hello,
Have not used the Vertex for a few weeks and now have Z axis issue.
It moves well in manual mode (from Repetier) but it seems not moving enough and prints quickly becomes a mess of PLA.
I have reinstalled Repetier and also applied 1.4 firmware but no joy.
How can I verify or reset Repetier settings, or any other suggestion ??
Tx 
Finally, my problem was
- an incorrect stl file, with one part not touching the ground
- some misalignement of the bed, being not perfectly horizontal.
Now working again fine
BR