OK Guys, I'm new here so bear with me. I have been fixing small engines for many years and this one takes the cake!! I worked this summer for a lawn care business as a general help for the crew and repair person. He uses two 48 inch cut Ferris walk behinds. When I started one was already down,, It had the exhaust valve guide on the #1 cylinder slipped and bent the push rods so the head had to be replaced. Engine was clean and the fins were not obstructed. Well, within 3 or 4 months the other Ferris did the exact same thing.. I am now waiting on a head for it as well. Like another member I read Kawasaki states it is Operator error and will have no part in it. The guy on the phone questioned my ability and pretty much was rude. If you know the Ferris,, the #1 cylinder has the muffler and the cross section of the exhaust pipe inches away but the #2 is clean and free. Kawasaki is at fault for the design of the muffler or Ferris for the design of the mower, I don't care. Anyone else having this problem?? PS one has around 1500 hours the other has around 2800 hours and valve adjustment was good. I tried to eliminate anything they could tell me. What can be done to help the new heads survive?