Its hard to sa anything without seeing the footage or the system. But Ithink yout vibrationdampener is not working well ... What kind of shaking do you have? How is your Gimbal mounted upsidedown or normal? What kind of dampener are you using? Wire rope or rubber? You can adjust the Gimbal by the software or app. The settings depends on your setup. I´m using a red epic with a 18-50 with 3 lensmotors and my settings are Tuning Pan 50 Tilt 30 and Roll 35. I´m using it in handhald mode.
That looks realy heavy ... Ok, first of all I think your wire rope is to thick. If you use a rope that´s too slow-acting it won´t absorb the vibration. Take a thinner rope and make it shorter then the old one. 2nd you can´t adjust the spring on diffrent weights so make one end fixed to a screw, so you can change the pre-loading of your arm when you turn the screw.(Don´t know if it´s understandable) We have changed the spring to a pnymatic zylinder with a ventil to fill the air inside. 3rd you need a oneway oilbreak, to stop the swing of the arm. http://www.weforma.com/de/daempfungstechnik/vorschuboelbremsen/wm-vd.html Have look at www.gimbalworks.de
This one here is from "infinity hobby" for 200USD.. http://www.infinity-hobby.com/product_info.php?products_id=12530
What mounting hardware are you using?? I've been looking all over the place for a good option kit, and I haven't found one that looks durable enough,