I noticed that the v9 extruder flexes and moves a lot when extruding/reversing.I modified the idler and driven parts to strengthen the extruder, and stop it moving when the drive exerts force on the filament.After Camiel uploaded the new 0.4 stl's, I have made the driven holder the same. No changes over his design.Also, adding an extruder corner next to the idler strengthens the whole extruder a lot. The aluminium base will need drilling out to fix. Easyist way is to align and fix the corner in place with the drive plate, and drill down through the hole in the corner and into the base plate, then bolt corner to the base. This seems to be done on the Orca 0.4 so it can't be too bad a mod. :)Print and assemble as normal, but the idler slots into the driven holder, (with about 0.5mm clearance.)