Z axis stutter
I am running an MK2.5 and have this stutter in the Z axis. It causes a line in the prints where it appears to just print multiple layers without moving the Z axis up. While in manual, if I crank the knob to rapid travel up, around 15mm off 0, the Z pauses just for a fraction of a second. I broke the guide rail brackets loose and manually rotated the screws by hand to check for binding and everything feels perfectly smooth. Just now, I powered the printer down, manually screw the Z axis about halfway up, then powered back on. The printer then by default assumed I was at 0 position when I was halfway through the mechanical travel. I cranked the knob to move Z up and right around 15mm off of where I started, I noticed the stutter again. I feel I have ruled out out mechanical issues now and this has to be a driver or electrical issue but I cannot figure out what could be causing this. Any help would be great, thanks.