Just so everybody knows
its button 14 that does the Feedrate override reset.
So making a macro would go something like this:
Open up the VB Script editor in mach 3, make a new file for your macro, I called mine m300.m1s
and type the following in:
DoButton(14)
Save it in the macros folder under the profile you are using. Now to use it, just add the M300 to the Gcode you are running and thats it. You can try if it works by overriding the feed rate and typing M300 in the MDI line, it should reset to 100%
To some, this is pretty trivial, but for beginers (we all were at some point) it scares us to try and do something like this. But if we try simple stuff like this, we can get more confortable with things like this, and try their own modifications.
Thanks again
Fernando