Small Engines (Lawn Mowers, etc.): MTD Riding Lawn Mower Does nothing when you turn the key, riding lawn mower, jumper wire

Question
My solenoid has been replaced in 2001, and 2003.  Now, my MTD Riding Mower is not responding when I turn the key... this was the same condition when the solenoids were replaced in the past.  Could it be the solenoid again?  Why would my solenoid be going out so frequently?  Is that normal?
Thank you.
MTD Model 136L660F062  [95178]?
Purhased April 1996
Transmatic Front Engine Lawn Tractor
Model 600 series Lawn Tractors

Answer
Hi Jean,

Very sorry for my delay.

Yes, it could be the solenoid again.  They just fail sometimes.  Follow my No Crank proceedure below to be sure and check the other components.  

I would check the starter first.  Jump the positive battery terminal to the starter and it should crank over. If so, skip to step 2.
If not, jump from a battery that you know is good, from a car.  If still nothing, the starter is bad.  If good, then the mower battery is weak.  

Step 2.
If the starter and battery are good, you will need to trace the entire circuit from the starter to the battery.   The solenoid, switches the battery power to the starter, when power from the key switch is sent to the small terminal on the solenoid. To test the solenoid, first make sure that you have power at its large terminal which comes from the battery. Then jump power from that terminal or the battery positive post, to its small terminal. You should hear a click and the other large terminal that feeds the starter should be energized. If not, then the solenoid is bad. If good, then continue tracing the power through the key switch to the battery until you find the break in the power path.   All testing can be done with a 12 volt light or a voltmeter.  Most equipment has safety switches in  the seat and on the blade engagement lever. Check them by temporarily bypassing with a small jumper wire.

Let me know how you make out.
Michael