Recently I been having this issue where the extruder will not get up to 210 degrees. It will get to about 208 then fall back down to 204, then back and forth.
Meanwhile this is happening, the filament starts to smoke. So my thinking is maybe the sensor is not reading the right temp, etc?
DJ. Thanks for the info. Come to find out that the heating element was almost out of the hole and it brought the sensor out of the hole. The sensor was still close enough to the block that it picked up heat. Once screwed back in, no issues. Now I just need to relieve stress from that cable that runs to the motherboard. Thanks!
I had this same issue and it is good that you caught it. My sensor pulled out completely during a print and even though Marlin eventually cut if off due to thermal runaway it wasnt fast enough to prevent the heater from continuing to heat up so hot that the teflon in the hot end burnt and clogged my nozzle. I had to buy and reinstall a new hot end assembly. The one I got has a grub screw but it doesnt quite reach far enough to secure the sensor any tips to get it to work?