You might have better luck by posting the make and model number of the ENGINE you are talking about.

Walt Conner

Check your oil level - it may be diluted with gas due to a sticking/leaking float needle valve.

Most (maybe all?) STX38's have Kohler Command 12.5 or 13 HP engines. If you do not routinely close the fuel line shutoff valve when you shut the engine down, sooner or later you're going to have a problem of getting gasoline into the crankcase. I would try closing the fuel line valve, draining the oil, and putting in the correct amount of oil. Remember to re-open the fuel shutoff valve before trying to start the engine. If that fixes your problem, then be sure to ALWAYS close the shutoff valve when you shut down.

"Most (maybe all?) STX38's have Kohler Command 12.5 or 13 HP engines"

This is something that JD people may know by heart BUT there are those of us who know engines that do not know or care about JDs, just the engine they have on them.

Walt Conner

I realize that, Walt. I was telling the original poster. As you well know, many posters seem to think that a malfunctioning engine is directly tied to the lawn tractor manufacturer - not realizing that the very same engine might be installed in any number of different brands of tractors, or that engine makers produce a variety of models. If their Craftsman won't start, the problem is with the Briggs & Stratton - or Tecumseh - or Kohler - or Kawasaki - or whatever - engine.

In the past, I have urged posters to name the engine manufacturer AND the model number AND any other identifying numbers - such as the Kohler Spec number.