Once upon a time I had under-extrusion issues with my DaVinci printer. Now I have an Nema 23 Bowden feed Extruder :) This is a remix of the original Nema 17 swivel mount (which was a remix of another bigger one) the point of which is to have as short a bowden tube as possible to reduce ooze. The bearing in the bottom is from a skateboard. I don't encourage sabotage, by teenagers look very funny scraping along the ground on only 3 wheels, it takes them ages to work out what is wrong!Print with about 50% fill as it takes a bit of strain when you push it together. Press the bearing into the plastic with a vice, it should be a tight fit.