I have just pulled the number 1 piston out of my car due to a failed leak down test. I was hoping to find a broken ring but no such luck (I can't believe I just said that). During the teardown I found no evidence of leakage on any gaskets. I did notice that the wear on the top ring is inconsistant around the ring. One part of the ring shows about 50% wear and on other places shows about 10% or less. Is this normal wear and part of the seating process? Cylinder walls look perfect and I have 1600 miles on the engine.