Troubleshooing Craftsman LT1000 w/Auto issues

I have an old LT1000 16.5 BS I/C with what I would have to assume is the original auto trans. I used it to pull an aerator this spring in my yard and ever since then the tractor feels "different". It's really difficult to put into words ,but after you ride/drive something for so long you get a "feel" for how it operates and you can tell when things change. It feels as if it's being "pulled down" power wise like something is sapping power from both the engine and the momentum of the tractor. Now as I stated earlier this seems to have started after pulling the aerator and when you pull an aerator , in case you didn't know, you pull it as fast as possible in concentric circles until you're so dizzy you feel like you'll fall off!    I immediately thought that I smoked the belt and it was glazed or something and not pulling efficiently and filed it away in the memory banks to remind me to replace drive belt cursing inwardly because I hadn't replaced it last fall when I rebuilt the deck and replaced it's belt!  

Now after stumbling across some others having a similar issue and saying that the transaxle is a very weak unit and doesn't like hills, heat, pulling etc... Now i'm a little concerned that I may have damaged my trans and am unsure exactly how to proceed. I've read that changing the fluid is a difficult and time consuming process that may or may not help. I really enjoy mowing with this tractor and would hate to lose it , but I'm on that hairy edge of spending TOO much on a tractor that is so common and not worth much to anyone but me.

I figured i'd post here because y'all have the most knowledge on various tractors of any group on the web and I've been following and lurking for quite some time. I have average mechanical ability , but, due to my age and lack of indoor working area my options are somewhat limited as to how deep I can dig into it myself and would most likely have to "farm" out heavy work to someone else. I'm not sure of actual serial number of this tractor as the sticker under the seat is worn off and I purchased it used. I paid $250 for this little tractor before last season and I've rebuilt deck, changed oil twice, tuned it up, bought a new hood, cleaned it thoroughly. It's in good shape overall , but, needs a seat and some paint to make it really nice. I drives and handles very nicely and is perfect size for my yard.

How would y'all proceed at this point if you were in my position??

THANKS!

try changing the oil in the tranny, it helped our scotts after it stopped moving.