I had an odd thing happen this week. While printing a piece on a spool that was almost empty, I heard a loud snap and when I looked at the printer, I saw that the filament had snapped off about 4" above the extruder? Not wanting to loose the print, I fed in the broken end when the filament got into the extruder and saved the print. This was my very first filament break in 4 years of printing.