finally solved the issue with my phantom "tail wagging" as you suggested ,try to lower the yaw gains, well I tried many lower settings to no avail but today I thought I'd increase the yaw gains, default was 100 so I've now put it at 125, plus calibrated it yet again and problem solved no more tail/yaw waggingOK,
More mass (gimbal), and non-centric CG. Gain adjust really sounds like the answer.
Please advise on your findings, results, etc.
TIA (thanks in advance).