I was printing something overnight, and the filament suddenly jammed. The machine 'finished' the print, however only the bottom half of the print was actually done. When I tried checking the filament through an un-load/load, there is a clicking noise and I am unable to load the filament into the machine. It only goes 1/2 way in then jams. How do I fix this? And, how do I prevent this in the future?