Problem changing nozzle  

Problem changing nozzle

Just wanted to share an experience I had yesterday.  I purchase some new nozzles and did a swap out from the 0.4 to the 0.25 and everything went perfectly.  When I went to change from the 0.25 back to the 0.4 I encountered a major problem.  

I undid the thumbscrews, which should loosen the nozzle to the point it moves.  I noticed it wouldn't move, but proceeded to unplug the 2 cables to the LoveBoard.  The nozzle still would not budge at all.  I decided to try to unscrew it in place, and it would turn, but would not move vertically.  The nozzle was completely stuck in the heatsink.  I worked with Prusa support and they had my try several things, but nothing worked.  The nozzle is completely stuck.  We tried heating it (up to 260).  We tried cooling it (I put the disassembled heatsink in my freezer).  I disassembled the Nextruder to get better access.  All of this to no avail.

I will say Prusa Support was great.  They stuck with me for hours and are going to replace the pieces that were damaged.  I really appreciate them and this is why I bought a Prusa.  However, I have no idea what caused the problem in the first place and can't imagine anything that I could have done that would cause this.  

I hopefully attached the picture correctly.  Unfortunately after enough heating, cooling, and tugging with various pliers, the nozzle snapped.  The metal rod is still stuck in the heatsink.  There is a copper ring (heatbreak?) that is partially in the heatsink and it appears has expanded to the point it will not move.  I don't see ANY excess filament anywhere, but I could be missing something.  

Any thoughts?