Pre-assembled unit with extreme under-extrusion problems  

Pre-assembled unit with extreme under-extrusion problems

Preface: I have been using a self-assembled MK3 for the past 7 years with 0 issues. I was excited to try out the Core One when my work decided to purchase one, but it has been nothing but problems.

Upon initial unboxing, there was orange filament still inside the extruder (I assume from a test print after assembly) that was extremely hard to remove. I ended up having to heat the hot end to 270 degrees and pull with all my strength to get it out. Once it was finally removed, I was experiencing extreme "skipping" upon attempting to load a brand new roll of Prusament PLA. After contacting support, they suggested doing a cold pull, which I completed. I also cleaned out any debris near the extruder gear, and this seemed to have helped as I can now load and unload filament easily.

However, I have yet to successfully complete a print. From my research it seems the heatbreak is getting too hot, causing back pressure and thus under extrusion after 5~10 min of printing (tested with PLA and PETG).

Testing possible temperature issues:The printer is in a room kept at 25 degrees. I have tried removing the lid, opening the door completely, adjusting print temps both up and down, setting custom gcode heatbreak temperature to 32 degrees, increasing chamber fan speeds: nothing has worked. With PETG (250 hot end, 80 bed, lid off, door open) the heatbreak reaches 42 degrees after 8 minutes and the under-extrusions becomes so extreme the print completely fails. PLA has similar results (230 hot end, 60 bed, lid off, door open), reaching 39 degrees after ~6min. Once the heatbreak reaches 40ish degrees I can hear the skipping start, so I'm fairly confident this is where the issue lies. 

Testing possible mechanical issues:I have tried recalibrating the planetary gears, loosening and tightening the bolts on the gear cover, adjusting the idler tension, cleaning the filament sensor, adjusting the bowden tubing, ensuring the spool/filament has as little friction as possible, and dropping print speeds down to that of my MK3. Again, nothing has helped.  

If anyone can offer any suggestions or support it would be greatly appreciated.

Here are some pictures a PLA print. You can see the print fails around the 15th layer. The first 10 or so layers look great.