I have the same problem. FYI, I am using 3 HS-65 MG on the cyclic, very solid no play at all. The tail servo is a HS-56, I will upgrade it if necessary. The wobble is obvious in hover, but not so obvious (or present) in forward flight. Idle-up is more solid. It becomes the worst when the battery dies down towards the end. I am suspecting that servos don't have enough holding power when voltage drops? I am really not sure. Please help. Thanks.