3GX with DS 919MG tail servo --- serious tail wag

[muscleman]

I just converted my 450 SE V2 to FBL. Bought a used 3GX from a member here. I have DS919MG tail servo, one that's supposed to be really good. The push rod is mounted to the closest possible hole in the round shaped servo horn. Push rod feels smooth by hand.

I think I set up the tail correctly with 3GX. 1520u frame/DS/REV. Limit is properly set. Delay set to 0.

When I had gyro gain of 67, it wags frequently back and forth. When I decrease it, the frequency of the way decreases but the movement of the wag increases. When it gets below 50, the tail gyro doesn't seem to really work anymore.

I haven't tried increasing gyro gain above 67. I should try that sometime today.

When throttle hold, if I move the tail to the left or right, the servo works to change the pitch. The lower gyro gain, the larger amount I have to move to make the servo move the same amount. Is this the right behavior?

Any ideas on why I have this tail wag issue? Is it possible to be a gyro/servo compatibility issue?

[muscleman]

Finally found out the cause. It was purely mechanical. When I hold the pitch slider arm tightly, and use the other hand to push back and forth of the pitch slider, it is pretty loose and can move for 2 mm.
I switched to another set of tail and the problem is gone.