I've been having trouble maintaining print temp with my e3d hot end... quite honestly I've never had much success with it. I got off two or three calibration prints before I started having a jamming issue (eventually corrected by chamfering the corners of the bowden tube) and I have since had trouble getting the hot end up to print temp (240). It takes about 20-30 minutes and then immediately starts dropping in temp to below 200 degrees. I'm not sure if this is a hardware (wiring) software (firmware) or user error (fan comes on) issue... I've tried everything and I'm ready to give up. I've replaced about 4 semitec thermistors before I got fed up and bought a screw in type... I've run PID autotune to 240. One of the other posts suggested that my heater block was screwed in to tight, so I loosened it a little and now I can get it to maintain 205... but its still below my recommended print settings. Any troubleshooting help would be greatly appreciated.