XK K120 How to calibrate?

Hello. I recently purchased yet another small helli, the XK K120, as i knew it was Deviated. Unfortunatelly it seems that something is wrong, and the calibrating procedure, doesn't seem to work as described in the manual, or as other suggest.

If i try to Calibrate 6G (with the switch to the 6G position, see attached file) and i hold both sticks down, nothing happens. If i hold both sticks in the downouter corner then the lights blink for a few seconds, but after that the flying is horrible. In fact it flys much worse in 6G mode than it does in 3D mode. In 3D mode, following the same steps to calibrate, it does fly significally better, but not good enough. And a couple of times the tail has gone crazy. Could be something wrong with the tail of course, but the fact is i am not sure i calibrate 6G and 3D correctly. I need to start from there. Does anyone know, and be kind to explain how to calibrate? I attach the file i use (which is a modified version from a file i found here, and i did have the very same problems before modifying it).
Thank you.

Ok, just to let anyone know, new versions of XK K120 calibrate both modes (3d and 6g) the same way, by holding the sticks to down outer positions for a few seconds.

In my case i found there was something wrong with the tail. I cut off the motor and tail plugs, and directly soldered new silicon wires to the tail motor. Also a tiny bit of CA glue secured the tail blade on the motor shaft (because i think it could be slipping from time to time). All this together, fixed the problems the heli had. It flys solid now. Thank you.