In case someone else with the same problem finds this post… I set up Estlcam to generate G-Code that can be directly sent to Pronterface without additional editing. In Estlcam under the “Setup” tab there is a “CNC program generation tab” you can change the way the G-Code is generated. The “Presets” tab you can change the File extension from nc to gco. There are more tabs under the “Texts” tab where you need to edit out the leading zeros from the “M” codes under each tab. And lastly, the “Commands” tab you can remove the leading zeros from the G Codes. Back under the “Presets” tab you can save these settings to a file if you wish.