I even called Troy Bilt with my model and serial number. The belt is what it was made with, supposed to be .5". Went to belt shop, showed him the pic, he agrees those are 5/8" pulleys. I got this mower from my mother-in-law, been using it for months til the belt went out. Seems it's had some deck work by the only TB authorized warranty shop around here. They must have replaced the pulleys with the wrong ones. She said she went through multiple belts in the 5 years she had it, but they were always replaced for free (with the wrong belt, it seems).
Of course my brand new battery was dead and I had to jump it last weekend when working on it. Today I finally get the right belt (2nd 5/8th's) and it doesn't turn a full spin jumping it. Cables and starter are hot to the touch.
