wow..pretty sad state of affairs, seldom see something like this from GWS.. I checked the web site (english version) and could find no resolution to those that already have the servos and are not comfy with the issue in their project. It will be interesting to see where they go with this in so far as a recall?
Sorry to inform you that we've been reported and found out that the carbon brushes of the motor used on the Naro Super D servo might get stuck when widely operated by the "Head Locking Gyro" which was normally used on the tail of 3D helicopters.
We're trying to update the motor used on it as soon as possible. The new batch of this servo with the newly upgraded motor will be released in the coming April or May. We're also trying to make them slightly different from the current ones. A sticker might be stuck on it.
While the current Naro Super D servos still work fine with sailplanes, slope gliders and another airplanes as well, however NOT for the tail blades of the 3D helicopters."