IMHO, I think you pushed that mower beyond it's capability (way too high,thick, wet grass) & trashed a deck drive belt in the process.

Might consider renting a bush hog setup or a DR brush trimmer to knock that area down first - then use the stx 38, which is a finish mower machine type.
If spindles, idlers, etc. all turn freely - replace the bad belt with an OEM belt (no aftermarket stuff) and keep on using the machine.

thanks RCBE - I'm guessing you're right... but just to clarify - this belt was brand new last year. Should it die so quickly, even if I push it too hard? I guess so...

If the machine is overloaded and the belt happens to be the "weak link", it will fail quickly - sometimes smoking badly, sometimes just stretching/shredding.

Also make sure you replace the belt with a new OEM (no aftermarket) belt. a few bucks more, but will usually hold up better/longer.

It is worth it to drop the deck and ensure that the rear pulley isn't binding so it can't keep tension on the primary. You'll also want to know that the lower end works freely and blades are sharp.

thanks again, guys. I replaced the belt, and things are working once again. i will make an effort this year to not attack the thick grass quite so aggressively.

so get this, folks - the same thing happened today with my "new" belt - the blades were unable to cut the grass and the grass is nowhere near as tall as it was last time. I tried to troubleshoot it, and was able to get the blades spinning again briefly, but the belt quickly failed again. When I turned the mower off, the belt was sizzling hot.

Now, to be honest, I don't really have too much of an issue replacing this belt once (or even twice) a year - this is an old machine that I inherited, and I had no intention of putting any sort of money into it. Right now my solution has been to replace the $20 belt every time I have a problem - which I can live with.

BUT: is there something else that could be causing my belts to fail so quickly? This time the belt is not pitted at all - it's just stretched, so that when the PTO engages, there isn't enough tension on the belt to turn the blades..
thanks for you help...

blades in good shape? deck underside not caked up with clippings ? Using OEM belt (correct cross-section/material)?
taking 1/3 grass cut off on each pass (approx)? Grass not damp (tires stay dry in cutting area)? Tensioner pulley pivot not dragging or hanging up?

one or a combo of above can put an undue load on the deck drive belt.

I will sharpen the blades. I cleaned out the grass clippings from the blade mechanisms. I am using an OEM belt. I need to be more careful with cutting less, shorter, and drier grass.

what do you mean about the tensioner pulley pivot? I'm not sure I follow on that one.

thanks for your help

on either an electric or manual pto setup , there is usually an idler pulley mounted on a spring loaded pivot bar to keep/maintain proper belt tension to eliminate belt slippage. look for such on your machine and check to see that the pivot is able to move OK. if it doesn't, belt slips - blades slow down - grass is poorly cut at best. slipping belts get hot - sometimes stretch - or fail.

do you mean the pivot bar that's near/attached to the PTO pulley? The one that creates the tension when the PTO is engaged? I think I saw this, and it seemed to be working... if not, what could I do to fix it?
thanks again

yeah, that's prolly it. Just make sure the entire pivot assy moves freely and responds to it's spring-loaded tension to properly tighten the belt when engaged.
Usually a thorough cleaning and lube with a little engine oil will mkae sure it's working freely. also chk that idler pulley for smooth rotation (bearing not worn out or wobbling).