Thanks for the suggestions, I appreciate the help. You have a clog, or more likely a piece of mechanical debris rattling around near the inside of the nozzle. Remove the entire hotend, and do cold pulls with Taulman 618 nylon until they come out totally clean. 240C in, feed filament by hand until it...

I've got a Prusa Mendel with a V3b extruder. The extruder replaced the old ceramic core one that came with the Prusa kit, and it's been working well since I installed it near the end of 2013. Lately, though, it's started jamming more and more often, to the point where I can't really print anything. ...