I just fully rebuilt a older nitro 4 tec. Model 4804. The car is belt driven. Both front and middle belts are perfect. The rear belt came loose. I've done some research and I see the rear is adjustable from the belt tension cams located on the left and right rear side plate. So I've taken the rear of the car apart and I see the adjustment point. My problem is the belt tension cam has a bearing that sits inside of it so as I adjust them it does nothing due to the bearing that just spins. Any suggestions appreciated!