To update this thread, I have itemized below what I have done to improve and fix the AP issues I was having. Hopefully this will help others who have been having the same set of issues.
1. Gimbal Flop: The new gimbal I received as a RMA did fix this issue. Just a heads up, it took three weeks to get a replacement gimbal as it came from China.
2. Excessive wobble (shaking of the gimbal which caused unusable video): Replaced noisy rear right motor. There is a thread on this forum on how to measure motor vibration and balance motors with mission planner. To be honest, just listening to the motor at different RPMs and feeling the vibration was enough to figure out which motor was bad.
3. “Micro-vibrations” as described by several members of this forum. For this issue I have done several things:
a. Adjusted the gimbal cables paying not only attention to the HDMI cable, but also the gimbal control wire harness. I used small tie-wraps to insure the cables were away from gimbal mount. Also spent time insuring the bend radius was correct on both cables. My measurement of success was the gimbal staying centered in the mount (not being pushed by the cables to one side). Also having free movement.
b. I also found that balancing the gimbal helped as I have a filter on my Hero 4 black. Just search on balancing gimbal.
c. Lastly I balanced my props.
Overall I am very happy with my progress. I might spend time balancing the motors to see if that tweaks out some additional vibration. However, post processing seems to take out any remaining micro-vibrations so I don’t feel this is absolutely necessary to have decent video quality. Of course this is coming from someone that is an amateur at AP. Here is a link to a video where I was flying out to an oil-drilling rig (not too close) to use as a “micro-vibration’ point of reference. The gimbal was at 90 degrees, which is the hardest to stabilize in my experience. Please ignore the props as I was pushing the solo at several points to see if I could bring out speed vibration.
Cheers