We've also got an AYP machine that is of teh same vintage, it's 13 years old and branded as a Poulon, but aside from cosmetic pieces and paint, it probably looks almost identical to your Craftsman garden tractor.
Most people either do not keep this price level mowers this many years, or if they do, don'tuse them for as many hours per year as I do mowing several acres on very uneven/steep terrain and doing other things with the tractor all year round (and possibly you too), so some wear issues have little to do with this particular brand, it's more of a reflection of the price point at which it's sold, which determines the level of "robustness" chosen for various parts of it's construction. I tow a heavy cart with ours to the extent that I've even worn out the cart's tires. We're probably both long past the calculated operating hours for the design life of this machine. But it just proves that with enough maintenance, some things can last a lot longer than anticipated.
The weakest parts that I've encountered, (the ones needing most frequent replacement/adjustment/repair) of this AYP machine are the front suspension/steering parts, most notibly the steering shaft and sector gear and front wheel BUSHINGS (they call them bearings), plus pulleys and certain blade related parts, such as spindle bearings (which I replace separately, instead of buying complete spindle assemblies).
I've had very good luck getting nearly every part I've ever needed through local auto parts stores (belts and spindle bearings) or from either Outdoor Distributors (easier site to search) or Pat's Small Engine Plus (cheapest source of the best aftermarket hi-lift non-mulching blades Stens 340-070 for the 46" deck and some parts but shipping usually takes longer) Both have searchable model diagrams that will help you to find the exact part that you need-if you don't have the manual to begin your search for the correct part number.
One tip, some/many/most the original Craftsman or AYP part numbers have been changed through the years, so if you don't find your exact part number, try to be sure on the drawings that it still appears to be the right part when you have to order something with a new number. Also, I believe that the original manufacturerer (AYP) has been bought out. I think Husqevarna is who actually owns AYP or AYP's old parts stock right now and if so, they will likely soon be using at least a different prefix for many/most/all of the parts that come from their warehouses to the various resellers (such as Outdoor Distributors or Pat's).
In re. the belts self destructing, there are several reasons why this can be happenning, all of which have happened to our over the years, and some have already been mentioned, others not.
Pulley problems:
bearings on the pulleys that have them will eventually wear, causing the pulley to wobble or drag and eventually seize. The belt notch ( V) of the stamped steel pulleys will also wear eventually (especially if you have sandy soil or cut anything or in any conditions that produce a lot of dust), getting deeper, smoother and also thinning the metal itself. When it gets deeper, the belt will ride lower in the V, slowing the effective belt speed, often slipping more and more as the belt wears it's edges to conform with the steeper angle that the pulley sides have worn to. All these will accellerate belt wear, and increase belt "slap" making the belt more likely to regularly contact somthing metal nearby, such as the belt guides. Look for shiny and worn metal parts close to the belts travel path.
On the main drive pulley (the long shanked engine pulley) when this happens, the pulley can start to split, wobble, and even start to chew away at the belt if the split opens up enough. The main drive pulley sometimes is not a perfect fit on it's shaft, and if so, it will be wobbling continuously, which accellerates belt wear, so look at it closely with the engine running.
Other belt problems:
Using NON-OEM belts requires a different beginning length adjustment to the deck drive belt (not the on-board blade drive belt) as the OEM belt is inbetween the much less expensive standard 1" increment l&g belts. I'm assumingthat you do know how to do the length adjustment for this belt, as it's required as any belt used for this wears and stretches in use and the deck drive will start to slip with a loose belt, making the blade speed noticibly slower as will V notch wear to the main drive pulley). I opt to use aftermarket belts because I rerely lose a belt to it's being worn out, they usually get cut from debris I pick up while useing our tractor as a roughcut/bush hog mower.
Another problem that may help to wear out the deck drive belt.
The suspension for this deck uses trunnions on long support arms that attach directly through holes punched in the side front frame members. Both the holes in the frame and the trunnions wear, requiring an adjustment to the arms to attempt to reposition the deck correctly, the problem is that if there is enough wear, and the belt tension is not just right, the deck is the being supported more by the belt tension than if the parts were not worn, plus it's still able to move fore and aft due to the frame holes being "egged" out and the trunnions being worn down in diameter, which directly affects the belt tension.
By the way, someone mentioned having to replace several spindle housings.
If you letthe spindle bearings get too worn/dried out before adding more grease to the spindle housing to replace that which will eventually come out of the bearings (even sealed bearings grease supply doesn't last forever) or replacing them, they can self destruct or seize and since the housings are aluminum they can sometimes overheat to the point that the metal of the housing will distort, which can make a new one loose in it's recess.
Mowing rocks, stumps, half buried steel debris, and large diameter branches more than occasionally can also damage the spindles. Whatever bent a blade can sometimes also bend the spindle shaft it's on, as they aren't very stout. Also, if forgetting to replace worn out or distorted circular ring sheetmetal grass guards on the bottom of the mower, this is more likely to happen. I've replaced ONE spindle housing assembly in 13 years, (have replaced all the grass guards one time though) and that was before I knew that the bearings were actually a standard type and size that could be obtained locally and could be removed from the shaft reasonably easily.
But spindle assemblies aren't that expensive now either-maybe they're coming from China and don't last as long as the older ones did?
Hope this helps.
I have yet to not find parts for any Craftsman tractor. There are so many of these things out there that most small engine shops have piles of them out back for spare parts assuming you can't otherwise grub up a replacement from either SearsParts Direct or eBay or similar.
