Craftsman LT1000, 12 hp briggs & stratton will not start. If I try to start it the engine will not turn over, it make about a quatyer round or less and stop. If I take the starter off and turn the key the syarter spins. If I take the spark plug out and trun the key the engine turns over like it should. I am getting fire at the spark plug. I don't know if I have a weak starter, if there is such a thing or if I have other problems. It started and run great a few days ago. I also had the battery tested and they said it was good. I don't know how to test a starter and don't want to spend money on a new one if it is not the problem. Can someone please give me some advise.

Hi,
Time for the valve adjustment, be it by you(if capable) or other. See this:
Lawn Mower Repair Valve Adjustment - YouTube (http://www.youtube.com/watch?v=NjzX-PUjKmo)
As always, Peace,
Clarke