Small Engines (Lawn Mowers, etc.): Problem to start Murray lawn mover tractor, lawn mover, spec numbers

Question
I have a 12.5hp Murray (40507x8a) rider. When I am trying to start the engine at first there is no no cranking or movement.
If I keep holding the key in the starting position about 10 sec. later the flywheel motor will slowly start to rotate but not quick enough. At first it seems like a dead battery but the battery is fully charged. I checked and cleaned all the contacts (including grounds) but that did not make any difference.  Is that a bad solenoid or maybe it is time for new stator/motor?  Another peace of information: when lawn mover was working my battery seems to drain quickly after a month or so. Does the battery supposed to recharge while the mower is working?    
Appreciate for any help on this matter.

Answer
Hello Alexander:

Send me the Model and Type or Spec Numbers Off the Engine, Please. With these I can Locate the Proper Manual and Better Assist you. The Mower Breakdown Does Not List the Engine Model for me to Locate the Engine Breakdown. From your Description, it Sounds like the Starter is Dragging. The Longer you Hold the Ign Switch Engaged the Hotter the Starter Becomes and it Will Slowly Start to Turn the Engine. If this is an OHV Engine the Valve Clearance May Require Setting. If the Valve Clearance is Off the Compression Release will Not Operate Properly and Cause the Problem you Described. If the Battery is Not Staying Charged, then the Stator/Alternator/Regulator May be Bad or the Battery May have a Weak Cell that Draws the Battery Charge Down. Go to this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM (Murray) and Enter the Model Numbers (40507X8A). Then Double Click on your Model in the Results Area. Then Select the Section of the Mower you Wish to View. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John