Hi, I just purchased a E3D V6 direct 3mm, hotend, managed to get it fitted and printing very nice, yesterday I printed an 4 hour print, all went very well, then changed filament to a different colour (one I have used many times before without problems), about 30 minutes into the print the hot end became jammed, I then removed it from the printer and the only way I could free it was to burn it out, or so I thought, the nozzle is completely jammed, I have burnt it out also soaked it in acetone but it is still blocked, any ideas please