I hope this is the correct forum for my issue... I have a LONGER3D LK4 Pro that printed normally for months. And then one day I noticed the plate and print head trace the path of the object without laying down any filament. I suspected a clogged nozzle, but I can push filament thru it with no problem. Then I noticed the knurled drive wheel that feeds filament just rotates back and forth in tiny movements--it is definitely NOT drawing filament. LONGER3D.com has no support information on this topic that I can find. I have absolutely zero idea how to t'shoot this issue further. Suggestions? Recommendations?