PTFE tube coming loose

Lee Rossi

So this has happened repeatedly this morning - I've dismantled the nozzle and checked there was no jam, but now whenever I start to feed in new filament or start to print the ptfe tube pushes free after a couple of seconds. Is this a faulty part or indicative of another problem? 

Laser8302

Looks to be either 
1) Bad PTFE tube end. Cut a bit (~10mm) off the tube and re-insert it.
2) Bad coupler. replace the extruder coupler.

Samuel Pinches

If you unscrew the coupler from the extruder, if you look inside you should see a metal tooth ring. If this ring is fractured or snapped, it will not grip the bowden tube. You may need a replacement: https://sampin.ch/bowdenali

Make sure you're pressing down the black ring as you are inserting the tube, so it can grip properly.

Lee Rossi

Looks to be the coupler gone completely (after two hours of double checking). 

Richy_T

These get damaged really easily when you remove the PTFE tube. The A1 is slightly different but I had the same issue. I recommend keeping some spares on-hand.