The valves on the manifold body of the iManifold may appear to be leaking, however, it is most likely the grease that we use to lubricate the valve stems. The valves are diaphragm type and the stem simply pushes on the diaphragm to open and close the valve. We grease the valve steam for smooth operation. As the brass oxides the grease turns darker in color. We have had this manifold design for over 30 years, they do not often leak. After looking at the photo, if you still think you have a leak, please verify with soap bubbles as your electronic leak detector may be cross sensitive to the silicone grease we use for lubrication.