I'm thinking a mouse nest under the engine shrouding. Those meece just love to build their nests in there, and they even have an area to use as their toilet! If that has happened, the cooling air can not get down around and through the cooling fins on the cylinder and block, which then causes excessive heat build-up inside the engine, and that causes the engine to bind up, and cause more heat. Left go too long, and you'll be looking for an engine! Brfore buying a new magneto, or carburetor--check under the engine shrouds. Might get a surprise! I opened one up and found mother mouse in the last throes of child-birth! She and her kids didn't live long enough to become a problem!! "STOMP!" And, next fall, when you put it in storage, stuff a couple clothes dryer sheets in around the engine shrouds! Mice hate the smell, women love it!

Thank you for the advice. I tried touching both heavy terminals on the solenoid with a screwdriver, got some sparks but no movement of the starter. I checked the voltage on the battery and it is still ~12V. I connected the battery charger to the battery and got the voltage up to near 15V then tried the touching the screwdriver to both heavy terminals again. Now the starter moves a little but in a way similar to my previous tests. Could it be a bad cell in the battery even if it is putting out 12Volts (or 15 with help from the charger)? I was talking to a co-worker today about the problem and he told me that most lawn tractor batteries don't last more than 4-5 years. The one in my tractor is original and a little over 7 years old. I remove the battery every season and store it in my basement. Before replacing the battery every season, I charge it up. Given all the information you gave me yesterday and learning that my battery has lasted a few years longer than is usual, I'm back to thinking it could be the battery. Before you told me that connecting a charger directly the starter doesn't necessarily provide enough juice to turn the starter, I'm back to thinking the battery could be bad. I'll buy a new battery tomorrow because it could be the problem. Even if it doesn't fix the problem, it sounds like it's time to get a new one anyway. Thank you, Scott

I take it that the engine does not even TRY to start, but just spins when the starter is engaged. You need to make the test that mownie suggested. There are probably more safety interlocks than just the seat switch, and one of them could be "shorting" out the system. There is likely one on the clutch/brake pedal, and another on the PTO lever (the one that engages the blades), and one on the shift mechanism (to prevent starting if the transmission is in gear.) Testing these will require a multimeter. There is also a ground wire from the engine to the frame; typically on Husqvarna/AYP/Electrolux/Roper machines, it is a rather small black wire that is attached to the underside of the tractor frame just below the engine and inside the right front wheel. You've likely got a bad magneto or (more likely) either an electrical short caused by chafed insulation, corrosion, or loose connection, or a malfunctioning safety interlock switch. This all based on your being certain that there is no spark at the plug.

Have you actually had the battery load tested? IF not, how do you know it's good. Assuming a good battery, you might want to try removing the spark plugs and see if it cranks. GROUND the plug wires! There's a possibility (if a gravity flow carb) that the carb has leaked through, filling the cylinders with gasoline and hydro locking the engine. IF that's the case, you don't want stray sparks as gasoline is spurting out.