Answer: Our old Teflon’s tube part was not smooth enough to take the switch of the dual color. We have discovered it by analyzing some test and then we change the Teflon and the now the Teflon is divided by two parts. The tube parts are more smother now and it can easily pass the filament without jamming. If you have the single type old Teflon and having this issue please follow the video below to see how to make a new Teflon using old one and reduce the jamming issue.
new Teflon tube vs old Teflon tube