Setup for 4mm ID/6mm OD Bowden Tube (Ultimaker)

I had a problem with my original tube, it was a slightly small diameter and even the stock Ultimaker PLA wouldn't pass
through it.

I obtained a new PFA tube and ran into issues getting it to hold it in both ends tight enough (the original bowden tube is slightly larger on the outside). Hoping these instructions save you that grief! :D

As an added bonus the new tube is way less finicky about filament thickness.