Hi,

I have experienced a similar problem due to rudder control rod bind. Sometimes it would get caught in one (or both) of the plastic tail control guides (T-Rex 450V2). The problem was more frequent when the head was spinning fast. Slowing it down usually eliminates the problem. I have used 2 nylon cable ties for each control quide to restrict its movement (leaving about 5mm of free play area as the guide would interfere with the horizontal stabilizer) and a couple of drops of oil on the boom as well as the point through which the control rod moves. This seems to improve the situation greatly (and when I drop the gyro rate from 50 to 35% the problem goes away). I suspect minor balancing problems cause rapid vibration of the guides and force the rudder control rod to be stuck briefly (jerky rudder operation) causing the whole machine to shake. When the head spins faster the frequency of the vibration of the guides increases improving the chances of the rod getting caught.

Regards,

TVB