Problem with e-steps calibration


I’ve been using my K8400 for quite some time now and recently been having problems with the extrusion so I thought that a calibration would be good. Did the 50mm extrusion and found that it extruded almost 70mm. I have browsed through the forum and found that a change from 200steps/mm to around 150steps/mm would do the trick. When I do this my prints gets totally under extruded and the loading and unloading won’t work.
The topics concerning this matter are old and outdated and I’m surprised that Velleman hasn’t fixed this yet.
Does anyone have the changes in marlin to compensate this under extrusion? and set the printers software straight?

// Danny