I just go my new JD 757. Was reading through the owner's manual about the maintenance on the Kawasaki 25 hp. It says at 300 hours to take the mower back to the dealer and have the valve clearance adjusted, clean and lap the valve seat, clean combustion chamber, and adjust PTO clutch air gap. My dealer tells me that no-one ever does this and that he knows of no problems. The question I have for everyone is this.....do any of you do this or think it is necessary. It's not that I don't trust my dealer it's just that he does not sell too many of these mowers and I would like more opinions. Thanks! Grass is green....just as the mower should be!!