Small spindle crashed (SOLVED)

I did not try to leave those entries blank in the cam.

But I am assuming that a safe height is necessary for the machine to move to the cutting location.

What I could do is replace G0 entries with G01 (in the G-code file) that is related to Z axis prior to executing the G-code

On uptravel, you are fighting gravity. Excluding gravity and cutting forces, the motor works hardest when accelerating. Once at speed, torque requirement is < 20% of that.
Try reducing your acceleration and increasing your motor voltage if its < 48 volts