Small Engines (Lawn Mowers, etc.): MTD solenoid replacement, auto parts store, safety switch

Question
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Followup To
Question -
I recently replaced the solenoid in my Yard Machine 400 series riding mower with a 12.5 B&S engine which I couldn't get started since last season.  The replacement worked, and I was able to to turn the engine over a few times, and mowed for about an hour the next day. After stopping and shutting the engine off, I was unable to get the mower to start again.  

Do you know of anything that would cause the solenoid to go out so quickly, or could the replacement just be faulty?
Answer -
Does the solenoid click?  There could be a bad safety switch preventing the solenoid from receiving power.

Do you have a 12 DC volt meter?

Let me know.
Eric

Eric,

Thanks for your response. Unfortuately I don't have a volt meter, but if I can get one, what lines would you recommend testing?  

The Solenoid clicks may be once out of of every 10-15 attempts at the ignition switch.  After removing the panel where the shifter is located I found a safety switch (a grey plastic plunger switch with wires running to it).  Manipulating this switch while trying the ignition (holding the plunger itself at different heights on the switch) seemed to have an effect on the number of attempts that would get the solenoid to engage, but it's still intermittant.  I was still unable to get the engine to turn over even when the solenoid sounds like it's clicking.

Thanks for your time,
Jer  

Answer
Any brand volt meter will do...just make sure it has a 20-25 volt scale.  Some of the cheaper meters have a 10, 50 and 250 volt scale.  The 10 scale is too small and the 50 scale it too big.

For what you are doing I often use an inexpensive 12 volt test light available at any auto parts store.  

For most mowers there is one small wire on the solenoid.  This small wire is supposed to receive 12 volts when you turn the key to the start position.  The 12 volts energizes the solenoid which connects the battery to the starter which turns the starter.

If a safety switch is open, like the mower is not in neutral, the 12 vlots to the soleniod stops at the safety switch and thus the solenoid does not energize so the starter will not turn.

If the solenoid is clicking then the voltage is probably there but may not be enough.  This is generally caused by a low battery but more often the battery terminal and connections are dirty.  They may not appear to be corroded, but disconnecting them and cleaning the terimals and cable ends with a wire brush normally fixes the problem.

Let me know what you find.
Eric