UPDATED: sometimes the adapter crack when is bending the design is too fine, here is a Thick version, it work as a month with No problems, you need a m3 screw to lock in place the 6mm ptfe tube
Sometimes the little clamp of the PTFE on the feeder pop out, you can find a replacement on ebay, part name is Push Fit Air Fittings John Guest ebay amount PM0204E, more info on the fabtotum forum.
If your clamp is not broken, as a first aid you can bend a little meccano metal railing and lock with one of the screw of the feeder (photo).
This can be used to lock in place the clamp and the 6mm tubing which is continuously sliding out.
Size is accurate, sand in case you have problems inserting put the 6mm tube. There is a hole for lock the tube but you don't need it.
Hope is usefull it bend with a smooth curve, a nice side effect it keep the tube straight and decrease filament tension inside the tube, less oozing :-RRB-
my apologies for my poor english :-RRB-
print with https://youtu.be/OPka5OrWT6c
Rafts: Does Not Matter
Supports: Does Not Matter
Print at 0.165 fill 100% 1 perimeter
insert the Jhon Guest clamp and the 3mm tube,
On top slide the lock and screw to the feeder
Insert the 6mm tube, you require a m3 screw to lock in place the 6mm ptfe tube.