To those who don't have a kubota, the deck pulley thing isn't common; my zg222 with 250 hrs hasn't had a problem.
My mower had a recall on it's carburetor; apparently some were catching on fire. Have you replaced yours yet if your model is one that was affected?
EDIT: The 300 series gas mowers aren't much lighter than the diesel models; if you want to decrease weight, you would have to go with a 200 series.
spelled with a g!!!!!