I have the Sinjin PS unit apart. The case and covers are hard metal. Difficult to mark with a punch or awl. The unit only has two seals the are sealing the SW shaft. One is a quad ring or some call it an X-ring. The other is a dust seal. I have both of them out and took as many measurements as I could. I will take good, detailed pictures of everything and post them. I was always told, a quad ring should not be used as a pressure seal. The original quad ring has expanded or grown. It doesn't fit tight on the steering shaft. It also is thinner than the depth of the groove it fits into, which doesn't make sense. There are other O-rings I'll replace as long as the unit is apart. These O-rings weren't leaking. They are on the case and the hose fittings. I'll send everything off to that seal company I spoke with.