jump the starter solnoid, if it will crank , turn key on and jump again, if it starts then key switch is ok it would be the starter solnoid that's bad,
The first 6 digits of a Craftsman lawn tractor serial number will tell you the month, day and year it was built. So, if your serial number is 1599SO6258, your tractor was built on January 5, 1999.
Check for power at the clutch switch, then check for continuity through the switch with the clutch pedal depressed. If there is power and continuity, then the starter (or even ignition solenoid/starter relay) is the problem.
You will need a voltmeter. Hook the red cable to the + post and the black cable to the - post and it will show the voltage.
I can tell you little except that it is made by Husqvarna. They have Customer service toll free numbers, however.
Seat switch; it does not know the seat is occupied.
If you have to wiggle the shift lever in park or neutral to get the starter to crank the engine, the neutral safety switch is probably worn or out of adjustment.
you look at what model it is and look up when the model was made. If you could give more details maybe I could help better.
The most tell-tale sign is a single click when you try to start the engine.
I have not found a way to find that information yet. You can call Sears at (800) 252-1698. They may not be happy to just answer that question but they will.
The best way is by the number of lids or cells in the battery. Each cell is approx. 2 volts. 6 volt has 3 lids 12 volt has 6 lids.
Click the link for information on the Ford 9n tractor.
One of the first things I would check is if the batterys are dead. If they still hold a charge then check the wiring to the starter and if that checks out then the starter itself might be your problem. I can't tell you how to fix a starter problem but your local mechanic or John Deere shop might be able to help.