I had a Rambo running my machine and it started acting odd (seemed like the X axis was not working) I thought I fried a driver on it so I reflashed it with MM3DP software and wired it up on my MP3DPand it works fine. I replaced the Rambo with a RAMPS I had lying around on the MPCNC and ran some tests. No matter what axis I move first, it runs fine. The second axis I run rumbles and grinds like the motors are missing steps or turning opposite each other( they are not, I checked and double checked). The video give you an idea of what I am refering too. I moved the X axis, then the Y axis( grind, rumble) then the Z axis( grind, rumble).