I've had this Archer 2 for over a year and it has become increasingly harder to start, cold or hot. The engine has 400 hours but the carburetor was never rebuilt. Has anyone had this issue? I've tried various ways of prime, no prime, mixture rich, ICO. I live in Florida, sea level so have always been told primer shouldn't be needed. Mechanic is leaning toward a new carb but he's guessing. Mags have been checked for timing, plugs pulled and checked. Any help would be greatly appreciated.