Or you can do an edit all E's in the gcode and change to A. Or edit your post processor. I dont remember having issues with Mach 3 and printing.

I finally figured out my confusion when i got some g-code from someone else.  Apparently the g-code i generated myself left out all the extruder E commands. So now i see what i need to do.

Thanks,

using slic 3r for g code but mach3 z axes is giving + when it should be - how to change I have tried the hot keys but that does not work the z axes should be lifting not going down help please

Keith,  Config Homing/limits   In the Z row change the setting in the reversed column. 

Keith, after rereading your question..... In 3D printing the base of your table is the Z zero point.  Anything above that is a positive number.   So any and all 3D printing will be positive numbers as the Z axis moves up.  In mach 3 when you press the page up or Z+ jog button, the Z should go up.  You only reverse the axis travel direction if when jogging up, the Z goes down.