Summary

Hi, since I also have a CR-10S Pro was experiencing the issue with the PTFE Capricorn tube was pushed out of the PC4-M10 longer hrs of printing. This seems to be a combination of the softer Capricorn tube and the quality of the PC4-M10 fittings. After checking for high quality fittings, I only found one manufacturer and they would only ship in lots of 10 with a price at 5€/fitting…..
….so I was designing the double fitting setup which allows to just use two of the cheaper fittings in a row (so far no major issues again).
To assemble just screw in the first fitting screw the lower part onto the extruder, screw the second fitting into the upper part and then the upper part on the lower part. Finally push in the PTFE tube completely up to the extruder.
Do disassemble you have fist unscrew the upper part which will result in the fitting being pushed just along the PTFE tube. Then push the release ring on the first fitting to pull out the tube from the extruder. Finally push the release ring on the second fitting to slide down the upper part form the PTFE tube.