If there was some serious moisture inside the transaxle, then sitting for three years might have allowed things to rust up. There is no interlock that would prevent the shifting of gears.

The answer here is to pull the trans-axle out and open it up. Whatever is wrong is likely not all that serious. Any shafts that are rusted up can be cleaned up on a bench grinder with a wire wheel on it. The old oil can be washed out of the trans-axle using a solvent such as Varsol or equivalent. Once back together, refill the unit with the oil recommended by Deere. It's worth the effort.

Thanks for the info. I was hoping that I wouldn't have to tear into the trans, but I guess I'll have too.

There is a possiblity that the neutral safety switch or detent ball/ spring is rusted (on the top of the transaxel). It's something to hope for anyways. Try some gentle rocking while trying to shift. ARe you able to get it started and run it around? It really takes lots of time to clean those up. Yuk. I think that has Bentonite in it.

I tried to rock it while shifting back and forth, but that didn't work. I can't get it to start yet, I got a new starter for it, but I have really weak spark that I'm trying to pin down. Using the above advice about just being stuck, I was able to get it shifting again by GENTLY tapping the shifter linkage with a hammer, and voila, the shifter moves through the gears finally. Thanks for the advice. As soon as I figure out the weak spark, I should be up and mowing.

Here's a link for the Peerless manual. I don't know if it covers your model, but it will still be helpful if it doesn't.

Here is a link that might be useful: Peerless

That's good word. That Kohler might just need a little help to start. DO the basics: fresh fuel, drop the carb bowl anyway and get the old stuff out and look for water, refresh the plug. Try a spray of carb spray down the airhorn and cranking it - may just get it breathing again. Then, after you've driven it around for a bit- you may find it shifts better w/o having to crack it open.

After sitting for an extended period, the shift mechanisms
can become rusted/tight, as mentioned. I believe the STX
tractors used a Peerless model 915, which is the least
expensive/economy transaxle offered by Peerless. IMHO, it should have had a model 800 or 920 vs the 915 for the best
results, but I think Deere took the "cheap route" with this one to meet a certain price point with the STX30 & 38.
It DOES HAVE Peerless Bentonite grease (12 ozs.), which when left sitting for a period of time, can become harder
and thicker. Any moisture introduced can also exacerbate this problem with the grease. As "HEAT" and "USE" are introduced back into the unit, it should free-up some, but some shifter damage could also result while using it (shift fork, shift keys, etc.).

BEST OF LUCK !!!

T-Man

Thanks for all the input guys! Hopefully this will be running soon, so I can loosen up the trans. The spark plug wasn't firing, so I checked all connections for tightness and corrosion. I started going further into the wiring, when my dad suggested that I replace the spark plug. Plug looked, no pitting, discoloration or cracks. Just to humor him, I replaced it. Got spark! In all my years, never seen a plug look that good, and not work. Dad told me years ago, and I've told my sons, fix the cheapest thing first. Didn't follow that advice this time. Three days spent on a $1.50 spark plug!

Just posting a follow up to let you all know what happened. Got the engine running, but the trans is still having trouble. I can move the shifter back and forth, but it is in the same third gear. Guess I shouldn't of used that hammer, huh. So it is going to sit until I get the money to either replace it, or parts for it. Sorry for the late reply, but I don't have internet, so I have to use it at my work, and some weeks I'm not at a workplace that has internet.

Just an update on my mower. The mower starts and runs constant now. I replaced the battery, so now it will keep running without having to keep jumper cables on it constantly, but I still have to use a jumper wire on my starter, and I've replaced the PTO switch, had a John Deere tech check my ignition switch as well as used a jumper wire on every safety switch on the thing. Any ideas? I've also ran the mower up and down the street for an hour, the trans now has third and "in between". Not quite neutral, you can hear gears slightly growling, just not moving. Apparently, the trans is going to have to come apart, or replaced if I can find one cheap enough.