Weird zebra patterns of non-extruded filament  

Weird zebra patterns of non-extruded filament

First post. I am a beginner when it comes to Prusa printers but use other printers daily at my workplace. 

TL:DR, see images at the bottom of the weird zebra pattern I am getting recently.

So, this problem started a few days ago (well, more like weeks because I didn't have the time to fix it right away) and I've gotten strange behaviour from my printer. My prints went along fine and I've had several small prints and one "big" 24+ hour print. Recently all my prints have failed due to under extrusion. I've been going at it for 3 days now and I am starting to give up. I've tried a lot of different tips and even got an unopened fresh filament spool from work to see if I can solve the problem. Seemingly nothing works and I am starting to lose hope and patience. There has been no changes to the print settings in the slicer, in fact the Prusa logo print is the stock file bundled with the printer.

What I know:

- Zebra patterns and extrusion failure.

What I've tried to do to solve it:

- Removed the PTFE tube from the hot end AND the extruder housing to see if there were any filament leftovers, without finding any.

- Tightened and loosened the tension screw on the side of the extruder housing. Tightening it too much proved to help with the pattern, BUT;

- Disassembled the entire extruder housing multiple times to clean out the filament that got stuck when I tightened the screw too much.

- Tried to unwind a bit of filament from the spool to see if that would help the extruder, if the problem was that the extruder was too weak to pull the filament. Did not help.

- Tried both a glossy/smooth filament and a textured/matte filament. Matte worked a bit better but eventually ran into the same problem.

- Done about 50 filament purges and a couple of filament changes (glossy->matte and glossy->another spool of glossy).

- Tightened/loosened the extruder assembly screws. Tightening the assembly worked for a while.

I've tried to do each of these things separately and not all at once, to no avail. I might have done other things but I honestly can't remember anymore.

Thanks in advance! I'll gladly post more information if needed! I need all the help I can get, before I go mad.

Pictures:

Picture 1: A previous print from a couple of weeks ago. Glossy filament.

Picture 2: Latest attempt. Glossy filament.