Took the heater barrel apart and reconstructed, now with help of the BfB tutorial video
The result is a slightly improved, not to say less worse, extrusion. Now without hand-force, it extrudes very slowly. That is no more than four odd millimeters per minute.
Think I leave the RR arest for a while until I have an idea how to improve extrusion. As the sun shines today, it's time to go out and play.
Renoir's coach bolt solutio
Zach Hoeken's Pinchwheel Extruder prototype