JR 7703D Gyro Issue - Help

[RSKT8KR]

Gents,

TREX 600e with JR 9303 Spektrum and 7703D Gyro.

I cannot resolve a intermittent Violent tail wag.

I have had the Gain set from 53 to 90 with the same result.
The gain does have effect, but does not eliminate it.
The Gyro is mounted on the boom bulkhead as the instructions
indicate.

It hovers rock solid, If you pirouette left or right sometimes it
will start a violent tail wag (about 30-40 degrees).
If I feed a little left or right rudder it will stop 85-90% of the time.

Does anyone have any suggestions?

Thanks