Just a modified version of the original mk8 upgrade to allow me to use things that I had on hand instead of ordering / waiting for parts.
Update 2: Added versions for 623 bearing use (I do not have any 623 bearings so can't test it myself... please let me know if it needs to be different).
Update: Create one for the left side for those that have dual extruders and want to do both.
I was in my machine doing repairs for a thermocouple problem and noticed that my delrin plunger was worn. I did not really want to order parts and wait for them to come in to fix it so I modded the "Minimalistic Mk8 replacement" to fit what I had around the house.
I removed the spring and put a spot to use 3 "binder clip" arms to give the needed spring loaded pressure. I also adjusted the bearing area to allow for a 605 bearing (I had several in a bin full of RC helicopter parts), and made a printable pin that is a press fit through the arm and the bearing. I added a bit of a guide for the filament to make it easier to guide it in when loading.
Printed at 0 extra shells, .2mm layers and 100 infill. After it printed I cut the support away from the bearing area, installed the bearing and then put a drop of superglue on each side of the pin to make sure it didn't move after I installed it.
Have made a few test prints so far and it seems to be working quite well.
I only did the right side because I rarely print with my left extruder.