Most likely, you do not have enough pressure on the extruder drive gear, if you can manage to get it to print, you can print your own pieces. Worst case scenario is just order one from a hub on here. The one that came with my “Migbot Prusa I3” had a simple spring to apply the pressure, it was not strong enough to apply appropriate pressure cause feeding issues, so i removed the spring, and now use a machine screw to apply the pressure. Have not had an issue as of yet. I will post a picture of my setup today, and if you like it, i am more than willing to print you one.
