Hi Tomas,
looking at my copter and into Betaflight and also into other stabi's options, they have a possibility to calibrate the level of the 3 Axis zero point perpendicular to the Zero level / main rotor shaft.
I didn't find a similar option in the Spirit.
I'm using the Spirit by glueing it on the side of the heli. To meet the exact parallel gluing less then 1 degree to the main rotor shaft is difficult.
It would be much easier to glue the Spirit on the the heli, bring the main rotor shaft exact into the perpendicular position and press than a calibration button in the software.
Of cause, on my Goblins it is easy to find the exact position, because there is a platform for the Stabi. But this is not the case for my Scale Heli.
Best Regards
Bernhard
Spirit System
Support forum