I'm running a Super X4 with Mach3 for about one year now, just 2D cuts.
Recently the same problem is happening: when the Z axis is changing position, and it goes to the z safe axis clearance gap, the step motor makes a noise as if it was moving but not, so when the spindle plunges again, it breaks the tool, because the Gcode says +5 and it's -5 in reality,for example.
I tried on manual mode and I realized that when I attempt to move up the nose too quickly, it does the same noise and never move again. It seems like the motor is too weak for the weight...Thanks in advance.Gus