Outdoor Power Equipment and Small Engines - 17 HP Briggs wont run?

I have a 17 horse B&S engine on a 1742HS Saber by John Deere
Lawn tractor. This tractor is 5 yrs old and hasnt ran in 3 yrs.
I recently inherited this tractor.
I replaced the battery, cleaned the fuel tank and fuel lines, put in a in-line fuel filter and put in a new spark plug, then fresh fuel. Not even a putter.. So I then took off the carb and cleaned the bowl out and the main jet, everything looked like new, put the carb back on and still nothing, Now checking for spark I noticed all I am getting is a small faint one gapping from the most inner edge of the electrode to the inside corner of the ground wire...So I then proceeded to remove all of the metal shrouding around the engine to expose the flywheel and magneto, I removed the magneto and cleaned, reset gap with a business card, and cleaned outer magnetic section of the flywheel, still, what I think is a weak spark, nothing would happen..Could this be a bad coil?? HELP?? One thing I noticed is that the safety switch on the seat, I dont beleive is working it still turns over and has a faint spark there, with or without someone on the seat, deck engagement switch seems to be working, and the brake engagement switch seems to be working. THANKS FOR YOUR HELP!!!!!!! Randy

Well for one thing,if ether one of the safty switches wasn't working it wouldn't turn over at all.
NOW....before buying that ignition coil take the ground wire off the coil and try it.Wire could have a short in it.I've seen only one blade of grass short the whole ignition system out too.
If no strong spark after removing the ground wire....yep,the coil is bad.

Thanks for the tip!! I will try that and let you know how it went! Randy

I left the ignition switch in the run postion, battery is past dead, and the battery wont even charge,,I am getting quiet frustrated!!