Your trouble is that the inner plastic sheet sticks to the metal mandrel. And perhaps because the spiral wrap does wrinkle in the process to slide it out of the mandrel.
Try to smear a thin film of grease, butter or vaseline on the mandrel and then 2 turns of household plastic (over here trade name is Domopac) lengthwise, not spiral wrap. In this way the plastic slips on the grease and you can remove the mandrel. For me, with a bit larger tubes, it works every time, hope the same for you
If not try the same but on one end you put supplementary wraps of glass cloth around to build up a thicker wall, take a piece of hard material with a 1,8mm hole and hold the mandrel in a vice and use the hard piece as extractor. In this way you push the tube rather than pull it out.