Small Engines (Lawn Mowers, etc.): Craftsman riding lawn mower wont start with the key, craftsman riding lawn mower, riding lawn mower

Question
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Followup To
Question -
We just got an old Craftsman riding lawn mower with a 12hp OHV Tecumseh engine that has sat for 2 years.  We just replaced the battery and the spark plug.  If you are sitting on the seat, depressing the clutch pedal it won't start.  If I stay seated and leave the key in the start position and my husband touchs a screwdriver across the solenoid wires, the starter will engage and the engine will start.  We have replaced the ignition swith, but still no luck.  Our next thought is to replace the solenoid.  Does this sound right?

Also, the carburetor is filling up and gas is flowing into the air filter.  We are thinking that the carburetor probably needs to be cleaned and rebuilt.  Are we thinking correctly?

Thanks for your insight.
Answer -
It's more likely that a safety switch (clutch, blade or neutral safety) is either defective or out of adjustment.  The seat switch isn't typically part of the start circuit.  One by one, you can use a jumper to bypass the safety switches to find the defective one (engine should crank over when you've found it).  Yes, fuel flooding the carb indicates a clean and rebuild is necessary.  You are correct.  Hope this helps.

Follow up question:
Thank you for your quick response.  We only found 4 switches, a plunger switch under the seat, an ignition switch, a clutch switch and a brake switch.  These are also all of the switches shown on the Sears web site for model # 917-256321.  We bypassed all of the switches and the engine would still not turn over unless we bypassed the solenoid.  We bypassed the switches by looping wires on the connectors to make a constant current.  Is there another way that we should be bypassing them?
Thanks again!

Answer
That is the correct way to bypass the switches (just don't leave them that way).  Being that you have ruled out the safety switches, there is only one more check to tell you the solenoid is defective.  With the key held in the start position, there should be 12V (+) at one of the small terminals on the solenoid (use a test light with the ground lead connected to the chassis to determine).  If there is 12V (+) there, but the solenoid doesn't click, the solenoid is defective.  Hope this helps.