I have a 16HP briggs ELS on a Quick 36. I have had trouble starting it for a while, but now it seems very hard to turn over. I have a brand new battery and new spark plug. It seems like something is holding it back. I have taken off the drive belt and taken the clutch of the engine shaft, so I know this problem is when the engine itself. When I do get it started it doesn't sound right and it doesn't have the blade speed that it used to. It clogs up easily and feels like their is less power. Thanks in advance Matt.