I've been wrestling with a filament grinding problem for a few weeks now and I'm stuck.
The problem manifests itself as starting a print alright then extrusion stops while the printer keeps moving. When I pull the filament out I see indents from the gear then a depression where it ground down the filament.
Filament used is 1.75 mm Spool3D PETG on a Hictop printer, which is a clone of a Prusa i3. I don't know the exact part number though. The extruder is direct drive, and the 28 mm heatbreak is connected to a heatsink block rather than something with fins. Nozzle is standard 0.4 mm.
My print settings are quite conservative. Speed is 20 mm/s, retraction is 20 mm/s (though it never grinds on retraction), temperature is 255 °C, which is 10 °C higher than what works in my other printers. No print cooling.
At first I thought there was a clog, but I can push the filament though by hand quite well. I also use cleaning filament frequently and it never pulls out any debris. Heatbreak and nozzle have been changed to fresh items.
Does anybody have any other ideas of things I can try, or should I just get a new extruder?