How did you come up with your original value of 400? That sounds right for a Z axis screw drive but not for an extruder. Before I moved to Klipper, I had an E-step value of 135 in Marlin which, using the calculator I linked you with originally, gives you a “rotation_distance” of 23.7 which I used for the “measure and trim” procedure for Klipper (linked below) to get the 23.45 value.
https://www.klipper3d.org/Rotation_Distance.html#calibrating-rotation_distance-on-extruders
When you do “measure and trim”, I recommend you go 100mm, not the 50mm in the Klipper documentation.