Small Engines (Lawn Mowers, etc.): john deere stx38, safety switches, ground test

Question
okay, I bought a used jd stx38 with a kohler 12.5 hp cv12.5s motor. I bought it from an elderly man who keep good maintanance on it. It ran well for the first week, but now it won't start. by that I mean the engine turns over but will not start. I by passed the seat safety switch to no avail. Last I took the spark plug out and placed it close to the engine block and could not see a spark when motor was turned over.could there be something i'm over looking or is it a bad coil? thanks Jack Happy father's Day.

Answer
 Hello Jack:

 When Checking for Fire at the Plug. Wrap a Piece of Wire Around the Plug Threads. Connect the Other End of the Wire to the Engine Block, ie the Blower Housing Bolt Above the Plug. Place the Coil Lead on the Plug. On the Engine; Find the Coil Shut Off Wire and Disconnect it. It Should be on the Throttle Control Bracket Bolted to the Engine. Cover this Lead with a Small Piece if Electrical Tape and Leave the Wire in a Position that it Will Not Touch Ground. Test for Spark. This way the Coil is Isolated from any Grounds and if it Doesnt Fire you know it is Bad. If it Does Fire, then you need to Check ALL the Safety Switches. I have seen a Few Mowers that Were Wired Not to Start if any of the Safety Switches were Bad. I dont know why this is, I only know It Does Happen. Hope this Helps. Let me know what Happens, Please.

 Good Luck

 Respectfully

 John