My transmission will not shift into reverse. It makes a slight noise like it is going. I just drove it last night and it worked fine. I have a solid first gear and it shifts up fine but no reverse! I am thinking about tearn' it apart and clean the valve body. Anyone have any ideas before I dig in to it? This was a good used transmission I just installed last weedend. I changed the fluid/filter. I was impressed by how clean it was inside the pan. I would would be happy with any comments.