Small Engines (Lawn Mowers, etc.): 18 HP B&S wont start, cold cranking amps, auto part stores

Question
Well, it will start if I could get it to turn over fast enough.  I would suspect the battery except attempting to jump it off from a car is unsuccessful. Engine is 18 HP OHV electric start B&S in an LXT-1842 riding lawnmower. It has 247 hours and maintenance schedule has been followed. Oil level is full and although it is 3 hours from a change the oil is clean and clear. It just wont spin fast enough. There is an interlock switch on the brake pedal and one on the seat. Both "seem" to be working properly. The battery is dated 03/08 and is 275 cranking amps and 230 cold cranking amps. This winter I had to crank it a couple of times and was successful only after placing an electric heater close to the engine for an hour or so. It spun right up both times. I'm thinking bad battery, bad interlock switch or bad starter motor.
Your input please. Thanks in advance for your time.

Answer
Starter are fairly reliable.  The most common problem we find are poor connections and bad batteries.  Even though the connections may look clean, always disconnect them and clean both the battery cable ends and battery terminal posts with a wirebrush.  

Are you using the mower to push snow?  Cold weather can cause battery performance to degrade to the point where they will not have enough power to start the engine.  Battery Tenders really help keep the battery fully charged.  

Charge the battery with a battery charger, clean the cables/terminals and see if the engine will start.

You can also have the battery load tested at most auto part stores...usually no charge.  

Let me know what happens.

Eric