Thanks enaiman and Ceat for your responses!
Ceat It is also possible, that guiding problems (spikes) may be caused by this effect. This is obvious problem of firmware.
This is exactly what I fear.
I did send this to support two days ago, but have no response until now.
I also wish someone from ZWO would comment on this in this forum.
(Why are they so silent about this?)
I might send it to the support for a second time today.
If this gets not sorted out, I will simply return the mount.
Without good software (driver/firmware) a mount is not much use.
Matt