It's on a Ferris is3100, less than two years old and a little over 700 hrs. It has been at the dealer that we purchased from for over two weeks. A few weeks ago it stared making a tapping sound. We brought it in to have it checked out, they could not find anything wrong with it and said the sound would not hurt anything. Not long after this it lost power, so we brought it back to the dealer. They are telling us the camshaft is wore and needs to be replaced, also, a bent push rod. They are saying this is due to improper maintenance and not covered by the 3 year warranty. We change our oil every 50 hours like clock work, they said we should be doing it every 25 hours or whenever the oil starts to look dark. The manual says to change the oil every 100 hours. They are wanting to charge us over $500 for this repair. What are your thoughts.