My 2x has a very odd extruder problem. The right extruder works fine. The left will heat up when it should but recently has been cutting out right as soon as it completes its preheat. The change filament function and preheat utility will heat up and maintain the temperature of the extruder. As soon as the printer starts a print, either duel or left extruder only, the heater cuts off. So far I've created different print files from different computers through USB or SD card, exported through different versions of makerbot desktop, and most recently I downgraded then upgraded the firmware. All had no affect on the function of the left extruder. Any suggestions?