Small Engines (Lawn Mowers, etc.): clutch/brake pedal, craftsman model, clutch pedal

Question
when i depress the clutch/brake pedal the starter engages and starts the lawn tractor the key will not,just replace the ignition switch, solenoid and relay (craftsman model 917.255960) where should i look next had to hard wire the ignition switch since the connector had melted and seen no reason to buy new harness.

Answer
Let me get this straight, the key will not start the engine.  The engine starts when you  push the clutch pedal.

Is this correct?  

Do you have any idea why the wiring harness melted? This is very, very rare on garden tractors.

Let me know.
Eric