The Cream colored valve spring retainer on the right is covered with exhaust stain, It also will have the same stains are inside the rocker box cover and the paint on the outside will be darker or flaking off. The valve on the right should look like the valve on the left. Stains like this are tale-tale signs that the exhaust guide is worn beyond limits and would not pass SB388C. This cylinder could be dangerous to fly and would require the SB to be performed prior to releasing for flight. So far all of the marginal or worn out guides we have found will have this type of stain, this one is an extreme and just about to fail with catastrophic loss of the engine. Some will have just a little and be out of tolleance.