Dear Mach3 community:
I run a 4'x8' ezRouter Scorpion. Am a newer user (5 mos) cutting out primarily profiles of shapes and letters in plastic. My Z axis has been acting up for the past month, and I don't know where I went wrong. This week's issue is: each time I load a G-code and click START, the Z axis LIMIT SWITCH immediately TRIGGERS - I don't know how to overcome this.

Is the Z axis moving to a position to trigger the limit switch ?
Do you have any other limit switches ?
Is the spindle motor being turned on when you hit start ?

Tweakie.

Yes, on START, the tool travels upward to trigger the LIMIT SWITCH.
It looks like there are also limit switches for Y axis, but I don't believe that is triggering since the tool head isn't near them.
Yes, the spindle turns on when I hit START.

As your Z axis is moving to the limit switch then I suspect there is something in your Gcode which commands that move.

A couple of suggestions...

Check your Gcode for an initial Z axis move.
Go into Config. Safe_Z Setup and if that function is enabled then reduce the setting.

Tweakie.