I have a MP Voxel 3D printer. After a ten hour print I switched to some small fifteen minute prints. After a couple of these, all of a sudden, I’m hearing these strange grinding noises. Turns out it was the feeder trying and failing to feed the filament because the extruder wasn’t melting the filament. I’d only taken a couple of minutes to remove the plate so I could remove the print. Everything else works, just not the extruder. What happened and how do I fix it?