Anyone have any idea what could cause this?? Im new to big trailers with electric brakes. Occasionally under medium braking my goose neck trailer feels like its hopping. Gets worse if more brake is used and stops if there is room to let up. It is a Redrago 10 ton triple 7K Dexters with 6 electric brakes. Using a Tekonsha Sentinal controller. This only happens when loaded. It has done it so hard a couple times Im glad I had a seat belt on. Could this all be caused by warped drums?? I didnt turn them when I replaced all bearings and shoes because they were not that bad. Oscillating controller perhaps?? All wiring is new but the brakes have never been very impressive even when empty. Any ideas??????