Extrude motor loads but does not feed

Dear all,

I’ve been using my vertex printer for about 6 months now. Besides the occasional rookie mistakes i’ve been alright, but now i seem to have run into a problem i can’t fix by myself.

I had issues with no filament being extruded. When i first encountered it i thought it was because i was using bad slicer settings for temperature, feed speed etc…(i was switching from PLA to ABS at the time). After having reloaded original PLA from Velleman the problem persisted. I figured possibly the nozzle was clogged; this was the case. After cleaning and reinstallation of the nozzle i reloaded PLA filament (note: extruder motor works fine here…), PLA filament came out of the nozzle - confirming no obstructions - yet first print i try, no filament extrudes.
The nozzle heats up fine, XYZ drives work fine, i increased temperature from 190 up to 210 in steps of 5°C to see if that would help it “flow” better, nothing.
Finally i check if the extruder motor was working; seems that for some reason it is not feeding filament.
Any ideas on what causes this and how to resolve it ?

Thanks in advance for your feedback !

Check the screw holding the pulley on the extruder motor.
Is it tight?