Hi Vojtiš,
Great work ...
I've seen on your pictures that you have built against an additional reduction gear.
We have not had good experiences with it, because the gears are just not built for this torque, and it would still work when Walterson transmission. But then you should definitely stick to the gears on the drive axes, since otherwise this solve ever. I always use this owl 300 endfest. Simple screw lock or super glue is not enough.
regards Edwin