I have an early Ender3 - for so long that I’ve forgotten which actual version it is. It runs fine for so long, including repeat prints, but then it unexpectedly stops extruding. The filament feed motor just clicks, with the pla not going through; the extrusion head continues to ‘phantom print’. The heater, nozzle, and ptfe tube have all been recently replaced.
I have stripped everything down. The head is certainly hot, as my fingers will confirm, reading 210degC. The filament itself feeds through the tube ok; the 0.4 nozzle can be reamed when hot; but there is a hard plug of pla wedged above where the nozzle screws in.
Why is this happening? From reading other posts, should I just replace the tube (yet again)? Or is there something else I should be looking at.