Small Engines (Lawn Mowers, etc.): Slow cranking, will not start., code numbers, model type

Question
I have a 2003 model mtd 18 hp riding mower. briggs engine. It will only crank very slow if at all, and sometimes will make a revolution. It does this with a good battery  and have cleaned the terminals on the battery and at the starter. I have even tried jumping it with my car. Any ideas would be appreciated.

Answer
 Hello Lyndon:

 Have the Starter Load Tested. The Starter Brushes May be Bad. Testing Under No Load will Not Help. The Valves May Require Adjusting. Send me the Make, Model, Type and Code Numbers Off of the Engine, Please. With these Numbers I can Locate a Breakdown of the Engine and Better Assist you. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John