I have a FlashForge Creator Pro. I am trying to print PLA. What am I noticing is that during a print, it slowly accumulates PLA on the end of the nozzle. It starts to harden, and eventually falls over the end of the nozzle and doesn't allow filament to extrude. This is quite baffling, as I have done this print 3 times in a row, and now, on the 4th time, this is constantly happening. It's failed 3 times now. Does anyone have any clue as to why this might happen?!