I ran into a problem. I have converted my UM2E over to 1.75mm and 4/2 bowden. The top of the one part is fitted to connect with a 6/3 bowden tube. I was able to use an existing PTFE connector I had and a coupler to mate with the top of the metal tube, however it does not match up with your design. I also switched over to a BMG feeder and it is all setup to use 4/2 bowden as well. Any chance you can sent me your housing front in a step or other cad file so I can modify it for my use?