Small Engines (Lawn Mowers, etc.): Riding Mower Wont Start, starter solenoid, riding mower

Question
10 year old Craftsman rider with B&S 15 HP IC Gold engine has always started and run fine with routine maintenance only. Suddenly won't start. Turned key and nothing at all, not even a deflection on ammeter.  Had battery tested and replaced.  Also replaced starter solenoid and ignition switch.  Now ammeter goes full negative when I turn key to start, but starter wont' spin. Jumped from car directly to starter and it spins the engine over fine, although I blew the 30A fuse in the process and replaced it. Checked 3 "lockout" switches (brake, clutch, seat) and they are intact. Reconnected all wires, but no change. Tried following all wires to look for a bare spot and didn't find anything. Any ideas where to look next would be GREATLY appreciated. Thank you!

Answer
 Hello Alan:

 You have a Dead Ground. The Statement that the Meter goes Full Negative is a Very Good Indicator of this. Unplug Each Component from the Wiring Harness One AT A Time. When the Meter Stays at Neutral or SLIGHTLY to the Negative Side. That Component has Shorted to Ground. If you Unplug ALL the Components and Still Show by the Meter Full Negative, then the Harness has Shorted to Ground. If you will Send me the Model Numbers Off of the Mower, I May be Able to Locate a Diagram that Contains the Wiring Harness and the Components. Will the Battery in the Mower Turn thr Starter if Jumped From it to the Starter? Hope this Helps. Let me know what Happens, Please.

 Good Luck

 Respectfully

 John