Check for spark when it refuses to start. Some ignition coils are heat sensitive when hot. They'll provide enough spark to keep running, but not start. Also try loosening the gas cap for a few seconds in case it is a vent problem.

I also have an STX 38 and it has a push pull switch that controlls the PTO for the Mower deck. It is a knob thats right beside the key switch. You might check to see if it is in fact turned off. (pushed down) I'm having a similar problem in that When I engage the PTO with the Motor running and without the mower deck installed even It would kill the engine if I didn't disingage it. The pully does not turn at all???

As the satisfied owner of two STX38's, I have to say that one would have to be new and in the crate for me to consider giving $1000 for it. Don't get me wrong, they're great machines, but they've been discontinued for about 10 years, and those used ones could be as old as 20. Between the two STX's, the hydro is simpler to operate; on the other hand, the 5-speed is very reliable, and my wife has refused to replace her 5-speed with a hydro. The yellow deck is better in that the spindles can be repaired, while the black deck requires replacement of the spindle as a unit. Other than that, there is virtually no difference (I have one of each deck). The STX-38 was Deere's entry-level lawn tractor, as is the LA105. Personally, I would go for the new LA105 for the $700 difference in price, and get a brand new machine with warranty. With proper maintenance, it can last 15-20 years - one of my STXs is 18, the other 14. And, by the way, the LA105 sells for $1500 in my part of the country. Whatever you buy, keep in mind that proper routine maintenance is the key to reliability and longevity. There is no way to know what kind of maintenance has been done on the used lawn tractors.

Hey folks, so I'm posting this follow up in my original thread because I think I have a related problem. Last year, I replaced the PTO drive belt and the mower blade drive belts on my inherited JD STX 38 Yellow Deck. Today I took the mower out (NOT the first time this season) and had some serious issues. First of all, the grass is tall - 18-24 inches. I had the mower height set to the tallest height. The grass may have also been slightly damp - although not wet. I was able to cut basically one path, then I realized that although the PTO was engaged, the blades weren't cutting the grass. I was going at the slowest speed (first gear) and even tried cutting using only 1/2 of the mower deck width at a time - no help. I took the mower back to my driveway, cleared out lots of old clumped grass from the blades, and started the mower and the PTO. The blades were definitely turning. I turned off the mower again, and noticed that the PTO drive belt is looking terrible - it's all pitted and slack - it's not tight around the PTO shaft! So, my theory is this: the PTO drive belt is shot again (Although not broken yet) - so the blade spin when I'm not trying to cut anything, but when I come in contact with any sort of grass of substance, the slack belt is "slipping" and resulting in the blades not cutting? Does this make sense? Solution: replace the belt AGAIN???? A few more things to note: 1) I tried cutting shorter grass and drier grass and had very little luck. 2) why would my PTO drive belt, just replaced a year ago, be so shredded already? That's worrisome... any advice would be appreciated. thanks.