Ender 3 Pro, knocking sound from extruder motor on first couple of layers

My Ender 3 pro works nicely, but when printing the first couple of layers the extruder motor has a knocking sound every few seconds. As soon as i am up on layer 3-4 it goes away completely though. It looks like the extruder motor "jumps over" every time the knocking sound is heard. I cant see any flaws in the print though.

I cleaned out the nossle, but didnt find any obstruction, but since it is only an issue during the lower layers, could this be a bed leveling issue? If my nossle is to close to the bed, it might not manage to squeeze out the filament properly?

sounds like you're calibrated a bit too tight. The print nozzle is most likely too close to the bed. So the filament can't slow properly which generates back pressure, causing the extruder to skip as it can't puch filament trhough.
Once you've cleared the actual bed, the back pressure tends to go away.
Adjust your z-gap up by 0.1mm and see if that fixes it. :-)

Surprisingly the problem wasnt connected to bed height. I lowered the bed significantly(until the filament didnt stick) and the knocking continued. I took the extruder hot-end appart an re-assembeled it again, this solved the problem. I think what had happened was that the bowden tube wasnt pressed against the nossle hard enough, and that allowed for melted PLA to expand uppwards in the print head and start to block the filament.