Failing prints when extruding small amounts - help needed  

Failing prints when extruding small amounts - help needed

Firstly I'd just like to say after years and years of telling myself "I won't use it enough to justify it"; since I built my Core One I've been printing so much more than I ever imagined I would and I've been having a fantastic time with it.

Now I've been having a problem with some prints which dates back to probably the first weekend I had the printer up and running. It doesn't happen on every print but if you find a print where it does occur it will repeat the issue quite reliably. In fact, I have isolated a few scenarios and cropped the prints down to just the areas that cause this issue sort of as a benchmark to see if I could resolve the problem by changing variables such as print speed, door open, door closed, etc. However so far I've not had any luck which is why I'm here asking for help.

I have two videos demonstrating the issue along with a Prusa slicer screenshot of the area in question so you can see what's being printed.

Example One

0.15mm layer height; Prusament PLA (Galaxy Black and Prusa Orange).

This is a little character I was printing for my partner to show demonstrate the printer. It was unfortunately the first print I ever had fail.

So as you can see it cannot deal with the ears. The full model has failed like this 4 times. After cropping down to just the the ears I can get a failure after just a few millimetres of print height.

Example Two

0.2mm layer height; Prusament PLA (Galaxy Black).

This is more recent one I've recreated. I noticed in one of my real prints that while trying to use organic supports to support an overhang that was only about 1.6mm off the print bed. It caused the organic supports to be plentiful but tiny (presumably because of the lack of height) and that seemed to also cause the issue.

My Observations/Things I've Tried

• Once the head of the printer starts making that clicking noise it won't recover on it's own; even if it gets to a part of the print which requires heavy extrusion (you can see this when it starts to do the infill in the second example video).
• If you pause the print and do a filament change and just reload the filament it'll print again for a short period.
• I have recreated this with the door open, door closed. Door open and the window to the room open with the cold winter air flowing in the room.
• Heatbreak temperature being maintained below 32 degrees, still occurs.
• I have noticed there could be a correlation that the print cooling fan is at 100% when this failure occurs (because the layer takes less than 8 seconds to print).
• I have ran at a slower speed for these difficult areas, still occurs.
• I've done cold pulls until I get the 3 small filaments at the end nice and clean.

I'm hoping someone can help me work this out as I feel like I've run out of ideas.

Thanks for taking the time to read this far!

Adam