Even at stationary, I will sit on the backseat, and lightly pound on the front passenger seat, and hear the spring like rattle. So I know, 100%, that it is somewhere between the headrest and the upper portion of the backrest. Basically, when the backrest of the seat vibrates, the rattle starts. It doesn't happen on very cold days, just warm and hot days. I'd love to take the thing apart myself just for educational purpose if I have the instructions and time, but for now, I just want the damn thing fix. Greasedfolgore is right on the money. I put in every position. I still rattles.