I've had my U3 for about 8 months now, but I've mostly just been running dual extrusion PLA prints. I haven't printed with PVA in about 6 months. I went to swap out print cores today so that I could to a print with some PVA and I am unable to remove the core.
I remember it being tough to pull out before, but both myself and a number of students have been unsuccessful this time. I'm wondering, does it have anything to do with the different heights of the cores (seen in attached pictures). Printcore 1 is held higher as if it was going to be printing from printcore 2.