Dave,
There are several possibilities:
1. The switch actuator linkage is worn to the point where it will no longer move the switch far enough to operate the START contacts;
2. The clutch safety switch is not reliable;
3. The switch itself is failing;
4. The starter solenoid is failing.
The switch linkage is actually pulled upward to operate, not pushed downward as you might expect. The system looks something like this:
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Later,
Vader
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"
I'm'a do Things My Way - It's My way or the Highway."
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