Short-end feed Ultimaker Original upgrade

I have an old 3D printer that is produced by DFRobot Dreammaker, which comes from an Ultimaker Original 3D printer. It used to use a far-end feeder and had no hot bed. In order to print flexible materials, I modified it short feed system. I try to use the original extrusion head, stepper motor and fan. I used a lengthened built-in Teflon tube. The mounting seat was too close to the print head, so I used a 3mm board to separate the feeder.