I'm 2 hours into a 17 hour print and I heard the sound of the spool unwinding like it was birds nesting. I went over, and sure enough, the filament broke off and I had about 4" of filament sticking out. I had to find the tangle and get it back running again and hand feed it into the drive to it would catch. I sure hope that doesn't happen while I'm sleeping.... That would suck!!!