Small Engines (Lawn Mowers, etc.): john deere wiring question, amp fuse, starter solenoid

Question
I have a john Deere sxr75 lawn tractor, I have been fighting little issues here and there with getting this beauty back in tip top shape.
It has been running well. until 3 days ago. It will not crank, or even make any effort to turn over.
I have left the key on before and drained the battery before and figured maybe this was the case. I checked the battery and found if was at proper voltage, and even went as far as performing a load test to make sure I wasn't getting a false reading with no load, still good battery. I then checked the 15 amp fuse to make sure it is ok. fuse is good. I can jump the starter via cable going from pos. of the battery to the starter, and it will run, and shut off when the key is switched off. I have 12 volts at one side of the solenoid but only ground shows on the other side. when the key is cycled to "crank" I have no pos. voltage going to the starter, so I know my problem lyes either in the key cylinder, or other wiring in between. I do not know what wires are meant to carry pos, and what ones are meant to carry ground. so I cannot pin point what part to check and see what needs to be replaced. thank you in advance ..

Answer
How many small wires are on the starter solenoid?  Did you trace power up to the starter switch?

Take a look at the link below and let me know which starter key switch, usually a 5 or 6 pin switch with letters on the back of the switch housing.

http://www4.briggsandstratton.com/miscpdfs/RNT/alternator_replacement.pdf

Eric