Model 405004x99, 2 year old Tractor with a Briggs & S. 12.5 hp engine has a very hard time starting. It has a clean air filter; good in-line fuel filter, clean/fresh gas; oil is new and gets spark from the plug. I have had to jump start the battery from a car and (on a different occasion) a battery charger. I have a feeling the clutch is not operating correctly. The last time I drove it, I heard a loud "thunk" near the fly wheel gear over the mowing deck. It took me 1 1/2 hours to get it to start again. Strangely, it started when I shifted the speed control lever to TURTLE (extreme slow speed) and worked the choke in and out.. The engine sounds like it "wants to start" but is laboring to "catch". The murray manual at Murray, Inc. (http://www.murray.com) is no help-- min. instructions. The tractor has been garaged since Day 1, except for a period of three days/nights during damp conditions in the Atlanta, GA area during March 2007. Thanks.

It could be the selenoid valve just under the steering wheel. Its should have 3 or 4 wires hooked up to it. That's the same problem I had and I though it was the starter but it was actually the selenoid. You can get them at tractor supply for like 8 bucks.