I crashed mine and had the same problem.
I removed the gimbal and straightened it by holding the base and manually bending the gimbal arm a little at a time (this is difficult). Then remount the gimbal and camera and check for level through the viewer.
The section of the arm that must be straighten is between the electronics on the H3-3D (the little black box on the side of the arm) and the camera mount. If one only bends the portion between the electronics and the phantom, this does not correct the problem because the leveling sensor onboard the gimbal will try to compensate for this correction.
Later in the season, the gimbal was acting strange, got a deal on two new gimbals and bought two (one as spare) for $279 a piece.
