Small Engines (Lawn Mowers, etc.): Sears 17.5 B & S Riding Mower, flywheel teeth, hp mode

Question
Sears Riding Mower, Model No. 917.272.680
B & S Engine 17.5 HP Mode No. 31C707, Type 0230-E1.
I have had this mower for several years and for the past three years or so have had a problem cranking it.  The battery(GOOD) will only turn the flywheel a short distance before it quits turning.  You have to use another vehicle's battery to jumpter it off.  Even with the additional battery the fly wheel still only moves very sluggish and you have to keep bumping the key to make it keep turning and it will finally crank.  Once cranked it runs with no problem.  If the machine is cut off then you have to start over with the jumper battery.  Any suggestions: Thanks

Answer
Have you dis-connected the battery cables and cleaned the battery posts and battery cable ends with a wirebrush?  I have fixed a lot of starting problems just by cleaning the connections.  

Make sure you check and clean the ground (negative) cable where it connects to the frame.  I have also found work stater gears cause hard starting as the pinion gear will sometimes bind against the flywheel teeth but this is pretty rare.

Another common problem these days is  leaky carburetors.  If you oil smells like gas and the oil level is too full then the carb maybe leaking.  The engine would also smoke if gas was in the oil.  If the engine doesn't smoke then the carb is not an issue.

Clean the battery connections and let me know what happens.

Eric