Extruder skipping and clicking. No extrusion  

Extruder skipping and clicking. No extrusion

Well... funny thing, seems a lot to happen.

I have found an interesting reason why it seems to happen though. 
First I heard the clicking, but it only happend on the very left rear of the plate. I had my plate quite full with instances. 

I did not get extrusion and decided to to a filament unload/load and after this it went for a while again, untill one layer in the left rear again! 
Tried again... filament unload, load and go... 

Filament is PETG Matte... so it is a bit less easy to glide through the bowden. 
And why is it in the left rear and later also in the read middle. 

Well I opened the gears, they seem fine, but not the gear that is pulling the filament in.. there is metalic fine dust lying between the teeth. 
So my conclusion is this: 

- Filament was too hard to pull in... and the gear started to skip over it.
- Only in the left and middle rear, because the bowden on top of the extruder is bending there in a sharp angle.
- Filament matte is already harder to pull and in this very sharp angle, it just becomes impossible for the filament gear to pull it in and it starts skipping.

Pics and movie below. 

My solution so far is: 

- Clean the gears with a little copper brush. 
- Tighten the Idler screws in with 1/8 turn to give a bit more grip on the filament.
- Also I found out that the bowden tube was not going as was adviced here: https://help.prusa3d.com/guide/6-nextruder-assembly_849034#850678
But it went between the arm and the electric cables.
So that might have been contributed to the drag of the filament. 

Now test running with some flat models at the rear of the bed. 

On the most left back in the movie you see the damaged instance/model because of the extruder going over it without feeding. 
The clicks seem not to hard, but they were.