Original Chain Maslow - small Z-motor

So I am trying to figure out why my z-axis keeps moving the wrong amount - it seems that when I put in 1 mm (I have a 8mm lead screw - from the Another Z-Axis 3D print instructions) and the unit moves 5 mm. I run the motor test and my motors are not reporting back happy - they both move but then both say fail on direction. (The sled motors are also reporting as fail on first move but ok on 2nd?). Any thoughts or ideas?

Here is a post to the formula to calculate your z axis plunge.

I think I just need a new z-axis encoder… going to try that next. Currently the z-axis just goes so far because of time… it does not seem to move based on where it is at all… it currently goes about 5mm each move