Hi All, I replace the original shift spring in an 850T gearbox. It still had the original single loop shift return spring that would fail. I installed a new style spring but it turns out the spring legs were not even no matter which way I mounted the spring. Tried it in the box, but after the first shift, a spring leg popped over the eccentric in the rear cover preventing any further shifts as the pawl couldn't return. Fortunately I had a pawl with spring from a salvage gearbox where the spring legs were even. After going through the gearbox again it shifts well. If you are going through a gearbox, double check that spring legs are even. If not it becomes do it again.