Small Engines (Lawn Mowers, etc.): Lawn mower quits, tucumsa, plug hole

Question
I have a Craftsman Eagle 1 6.75hp (#917.377580)with a Tucumsa (143.986700) motor. All about 5 or 6 years old. I can start the lawn mower with 1 pull. It will run for about 2 seconds then die. I've tried to pump the primer bulb to see if it will continue to run. But the engine will continue to die. I have replaced the carburator, spark plug, oil & fuel. And I have opened the valve cover to view the valves to see if there was any viewable problems and there was none that was obvious.  There didn't appear to be any excessive carbon build up from what I could see through the spark plug hole. I have pulled the spark plug to check for spark but when I pull the spark plug it becomes very difficult to pull the starting rope for some reason. I have been operating the mower for the past 3 months and the mower would start missing out real bad after about 45 minutes of operating. The engine has a solid state ignition and I suppect this may be the cause. Please help before I pull out my hair on this one.

Thanks
Brian  

Answer
Brian, It may be that you have the beginings of a siezed bearing either on the crankpin or upper or lower bearing. If the sparkplug is removed and there is a "drag" when you are pulling it over .....You may have to completely take the engine apsrt......Bob