Unknown cause for under extrusion
I know mini under extrusion is not a new issue, but I have tried all the Prusa and forum-based suggestions. In simple this started after a failed print caused a blob of death and I had to replace the heater and thermistor and after this I had under extrusion.
this is a standard mini bought in March 2020. Initially I thought the issue to be heat creep, so I upgraded to a BondTec heat break and PTFE tube. This did not help the problem. Prusa support over the 15 hours I have worked with them have had me do countless cold pulls, rebuild the hot end, rebuild the extruder, make endless settings adjustments, three thermistors and heaters, two stock heat breaks, and endless test prints and calibration cubes.
The first layer is now going down perfect but as soon as it starts the second layer you can immediately see that it is under extruding. I have raised the temperature 10c on all filaments, but this does not help. We have checked the thermistors and heaters, and they are within spec. The visual calibration cube looks pretty decent but any print that I want to print turn out poor. The precision calibration cube shows five percent under extrusion and that is show in the e step calibration as well. Most recently I tuned the extruder E steps from 325 to 344 to no help. which supports the previous findings.
I am convinced it has something to do with a bad driver or motor but there is not great support for how to actually identify these problems.
I am completely lost and just want to throw away this printer but unfortunately, I love my two MK3S+ so am faithful the community can help me. Please let me know if you may need any other information to help make some sugestions.
First,
