Instead of fixing the 3D-Printer I ripped out the thermistor from the old heater, and now failed to remove the heatbreak from the block, to mount my di-whyed solution instead. truly a dark day for the laura.
It might be that the solution is to heat the thing to 250°C and use the pipewrench, but I don't think I have the energy for that today...
@la welcome to the "this is stuck and I'm really frustrated" club