random violent tail wag

[simon1]

I recently purchased a 130x from a forum member, it came with ds35 servo fitted as an upgrade on the tail. On first flight it had a massive tail wag to the point where it was unflyable, it looked and sounded pretty bad. I took the gain down a bit it, initially didnt make a difference at all still massive really fast tail wag, after about ten seconds of hovering it suddenly stopped and was fine?!. This has happened another once or twice, but everytime iv flew it, initial horid wag then stops.
Im getting tail drift to the left, im guessing that maybe because i have the gain so low.

Any ideas?

[tomatwalden]

Check that all mechanical tail components (ie. torque tube, umbrella gears, tail slider, etc.) are all working correctly and smoothly. Assuming that's all OK, I you've got to then look at the servo I'd say ...