Small Engines (Lawn Mowers, etc.): Engine (solenoid) clicks, but will not start, craftsman riding lawn mower, jumper cable

Question
Craftsman Riding Lawn Mower
Model#: 917.252501; May 1995

Cut the yard one weekend, and then next weekend the engine won't turn over.  I turn the key, hear a click (solenoid), but the starter won't spin and engage the flywheel;

The manual recommends checking the following, and here is what I found/did:

1) weak or dead battery; > no, fully charged;
2) corroded batery terminals; > no, very clean;
3) faulty solenoid; > no, replaced it with a new part, but got same result;
4) faulty starter; > not sure; bypassed it with a jumper cable, and I can at least get it to spin, but it will not engage the flywheel;
5) loose or damaged wiring; I have no idea...

a) The clutch/brake pedal safety switch works;
b) The blade engagement safety switch works;
c) Not sure about the seat operator presence safety switch; seat up or seat down, I still get the click.

Please help.  This is making me nuts.  I have already paid someone else to cut the yard once, and I am reluctant to take it in to the local repair shop due to past experience.

Kind Regards,

Rick King
Pleasantville NY

Answer
Remove the spark plug and try the jumper cable trick again.  If the starter spins but does not engage the flywheel then the starter pinion gear or clutch may be bad.  You can remove the metal engine blower housing to inspect the starter.  I rarely find bad starters.

As for the clicking, I would dis-connect the battery cables and clean the terminals with and cable ends with a wire brush...this normaly fixes the "clicking" sound you described.

Let me know if the starter spins, engages the flywheel with the spark plug removed.
Eric