Small Engines (Lawn Mowers, etc.): engine will not turn over, briggs stratton engine, toro wheel horse

Question
i have a toro wheel horse riding mower that will not crank over. serial number of mower is 6900586. model is 71193. it has a 14.5 hp briggs ohv quiet plus engine. i had the starter rebuilt and just put a new solenoid on it. still will not crank. motor will turn rotate by hand. battery is a year old and shows 12.4 volts. when i engage starter switch, the solenoid makes a vibrating noise and a low decible squeal. is there a chance that i attached the wires up wrong to the solenoid?  it has two terminals and two spade terminals. one cable goes from the battery to the solenoid and one goes from the starter to the solenoid.  there is a white wire that connects to a spade and a black wire that goes to a spade.  if the wires are hooked up correctly the only other things that i can think of are the switch and a little square black plastic box about an inch square above the solenoid that has two halves that plug into each other.  hopefully you can help me figure this out.

Answer
Hi Larry,

It doesn't sound good.  You must start by ruling certain things out.  
Make sure the switch is not the cause of your problem.

Check that all of your connections are secure.  

It would help if you had the shop manual for that particular Briggs & Stratton engine.

I would suggest that you check online with Briggs.  Make sure that you obtain the engine serial no. and model.

Sorry but that is about the best advice I can think of right at the moment. If you have a multi-meter you could check the current being put through the wires once the switch is on.

Regards,
Howard B.