Version 1.1 of the ArcWelder tool was released. Here's a new development snapshot that includes the new binaries. The new binaries should fix the plugin not working on some windows systems, as well as on OS X. It also fixes compatibility with the UM2 family of printers using UltiGcode (by moving the orginal gcode header back to the top of the file after processing).   Please let me know if this version processes the gcode for you, especially if previous versions would not. .