I have the dreaded kohler ch25s with head problems. Last year one of the the valve seats seized up, lifter stuck and bent a push rod. I fixed it for around 50 bucks. It has been running good so far this year until today when I heard a slight poppping @ the end of my last job. So, when I got home to do my own (last of course $$$$) it popped and puked big time and wouldn't even run. I'm thinking head gasket? It will run but very, very rough. I pulled the plug from the same side as last year and the it was mashed with no gap at all. It has over 2000 hours and I'm tired of screwing with it, I've got and emergency fund (Dave Ramsey) i'm thinking replacement. J. Thomas has them for around 1700.00 bucks plus shipping. Anyone replaced one of these. It looks like I just unbolt the old and rebolt the new. Is there more to it?